Random keystrokes (space, letters, Shift-combos) dropped only in text input fields, not in games — all hardware/software causes ruled out

Question

Body:

Hi, I've been dealing with a strange keystroke-dropping issue for a while and have systematically ruled out every common cause I could think of. Posting here in case someone recognizes the pattern or knows a deeper system-level explanation.

System:

• AMD Ryzen 9800X3D, RTX 5070 Ti, 32GB DDR5, Gigabyte B850M DS3H ICE
• Windows 11 (latest updates applied)
• Two different keyboards tested (different manufacturers), both wired, both plugged into rear/motherboard USB ports

The symptom: When typing quickly, individual keystrokes are dropped — mostly noticeable on Space, but also regular letters and Shift-combinations (e.g., "?" gets dropped while Enter right after it registers fine). This happens in Notepad, Google's search box, and AI chat websites (Claude, Gemini) — both in Korean (Hangul IME) and in English.

The most important clue: The dropping is pattern-dependent, not random.

• Typing the same word/phrase repeatedly at high speed (e.g. "hello hello hello hello") — no drops at all.
• Typing a sequence of different, unpredictable words at the same speed (e.g. "apple banana car computer sky ocean coffee umbrella clock tree") — consistent drops (missing spaces causing words to merge, missing letters like "banana" becoming "banan").

Critically: this never happens in games. I play fast-paced action games (Assassin's Creed-style open world, lots of simultaneous WASD + mouse + jump/dodge inputs) and have never once noticed a dropped input. This suggests the raw keyboard signal/USB transmission itself is fine — the problem seems to be specific to whatever pipeline converts key signals into text characters.

What I've already ruled out (please don't suggest these):

• Keyboard hardware — tested 2 different keyboards from different manufacturers, both wired, both on rear USB ports. Same issue on both.
• USB port/cable — same issue regardless of port.
• Browser extensions — reproduced in Incognito mode with all extensions disabled.
• Browser choice — reproduced identically in Edge and Firefox.
• Edge settings — "Web writing assistance," "text prediction," and "grammar/spell check" all disabled. No change.
• Windows Ease of Access → Keyboard: Sticky Keys, Filter Keys, Toggle Keys — all confirmed OFF.
• Windows text prediction — "Show text suggestions as I type on the physical keyboard" and "Multilingual text suggestions" — both confirmed OFF.
• Korean IME composition timing — reproduced identically when typing in English, so it's not Hangul-specific composition behavior.
• Background processes/apps — reproduced with literally nothing else open except the browser, and also reproduced with various games/apps running. No correlation.
• ctfmon.exe (CTF Loader / Text Services Framework) — checked Task Manager during reproduction; CPU usage stays at ~0.1–0.2%, doesn't spike meaningfully during drops.
• Keyboard debounce/anti-ghosting — ruled out since two completely different-brand keyboards show the identical pattern-dependent behavior.

What I'm looking for: Any insight into what part of the Windows text input pipeline (or browser text rendering pipeline) treats "repeated/predictable input" differently from "novel/unpredictable input" in a way that could cause this. Open to suggestions for deeper diagnostic tools (e.g., raw keyboard input loggers, Windows Reliability Monitor analysis, etc.) that could pinpoint where exactly in the pipeline the drop occurs.

Thanks in advance.

Answer 1

Hi gun woo lee,

I appreciate how thoroughly you've investigated this already.

Based on what you've described, Windows does not normally treat "predictable" and "unpredictable" words differently at the keyboard-driver level. The pattern you're seeing may instead reflect differences in key transitions and timing overlaps when typing unfamiliar sequences at high speed.

It's also worth noting that games often read input through Raw Input, while text fields typically receive translated keyboard and character messages through the application's text-input pipeline. As a result, the fact that games never exhibit the issue does not completely rule out a driver, filter, remapping utility, Text Services Framework (TSF), or user-profile-specific problem.

You may want to try the following:

1.Compare raw keyboard events with the resulting text:

Use a trusted keyboard-event diagnostic tool that records key-down and key-up events. If a missing Space or letter appears in the raw-event log but not in Notepad or another text editor, that would indicate the loss is occurring after the keyboard/HID layer rather than at the hardware input stage. As a precaution, avoid entering passwords while any key-logging utility is running.

2.Test in Safe Mode with Networking:

Safe Mode loads Windows with a minimal set of drivers and services, which can help determine whether third-party software is involved.

• Press Win + R, type msconfig and press Enter.
• Open the Boot tab.
• Check Safe boot and select Network.
• Click Apply > OK, then restart.
• After signing in, reproduce the typing test in Notepad and a browser.
• If the issue does not occur in Safe Mode with Networking, that would strongly suggest interference from a third-party service, driver, utility, or software component that does not load in Safe Mode.
• When finished testing, open msconfig again, clear Safe boot, apply the change and restart normally.

3.Perform a Clean Boot:

Even when all visible applications are closed, background services and filter drivers may still be active. A Clean Boot starts Windows with only essential Microsoft services and startup programs, making it easier to identify software conflicts.

• Open msconfig.
• On the Services tab, check Hide all Microsoft services, then click Disable all.
• On the Startup tab, open Task Manager and disable all startup items.
• Restart and test again.

*Disclaimer: A "clean boot" starts Windows with a minimal set of drivers and startup programs. It helps to determine whether a background service is interfering with your game or program and to isolate the cause of a problem. 

These steps of "clean boot" might look complicated at first glance. However, to avoid any trouble for you, please follow them in order and step-by-step so that it will help you get back on track. 

If the issue disappears, re-enable items in groups until the culprit is identified.

4.Test with a new local Windows account:

Since text input relies heavily on user-profile settings, this is an important test.

• Go to Settings > Accounts > Other users.
• Select Add account.
• Choose I don't have this person's sign-in information > Add a user without a Microsoft account.
• Create a temporary local administrator account.
• Sign out and sign in to the new account.
• Without installing any additional software or syncing settings, test the same typing scenarios in Notepad, Windows Terminal and a browser.

If the issue is absent in the new profile, the cause is more likely related to your current account's input-language settings, IME configuration, TSF components, browser profile or other per-user settings rather than a system-wide keyboard or HID problem.

5.Review third-party startup software, services, and drivers:

Pay particular attention to keyboard remappers, macro tools, RGB/control software, overlays, clipboard managers, security products, accessibility tools, motherboard utilities and peripheral-management software.

Sysinternals Autoruns can help identify non-Microsoft startup components. Using the Hide Microsoft Entries option makes it easier to focus on third-party software that may be interacting with the input stack.

6.Capture a WPR trace while reproducing the issue:

Windows Performance Recorder (WPR) captures detailed Event Tracing for Windows (ETW) data and can provide much deeper insight into the input pipeline than monitoring ctfmon.exe CPU usage alone.

Please let me know the results of these tests, as they may help narrow down where the input loss is occurring.

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