Hi,
With the issue description, I understand that you are getting problem with the Mouse on Dell OptiPlex 3020 Desktop machine I really appreciate you have tried the possible steps to fix the issue .Also I would like to inform you mouse and keyboard problem can have a number of causes like Cablesthat aren't connected properly, cables that aren’t connected properly, Incorrect device settings, Missing updates, Hardware problems.
So I would suggest you to follow the steps to fix the problem.
Before you follow the steps I would like to know? As you mentioned that you having issue with the specific user.
Is your computer part of network? Like home group or workgroup I would suggest you to please check and reply accordingly.
Method 1
Run the Hardware and Device Troubleshooter
The Hardware and Device Troubleshooter is an automated tool which checks the hardware connection on the computer for any known issues and provides the details on how to fix them. Follow these steps to run the troubleshooter.
a) Press “Windows Key” + “R” keys from the keyboard. In the run box, type “Control”
b) Control Panel will open up, now click on “Troubleshooting”.
c) In the “Troubleshooting” window, click on “View All” on the left pane.
d) Click on “Hardware and Device”.
e) Click on “Advanced” and then click on “Run as Administrator”.
f) Click “Next” and follow the on-screen instructions to complete the troubleshooting process.
Method 2
Install Mouse Drivers in Compatibility Mode
Try to install the Mouse Drivers in Compatibility Mode.
Follow these steps to install the drivers in compatibility mode and check if that helps.
a. Download the driver from the manufacturer’s website.
b. Right-click on the driver setup file and click on ‘properties’.
c. Click on the ‘**compatibility’**tab and check the box ‘**Run this program in compatibility mode for’**and select Windows Vista operating system from the drop down menu and proceed with the installation. Once this is done, restart the computer and check if the issue persists.
Method 3
You may also try Mouse Pointer Behaves Erratically If Mouse Pointer Speed Is Set above Level Five please follow the article.
https://support.microsoft.com/en-us/kb/267139
Hope this information is helpful. Please do let us know if you need further assistance with Windows, we’ll be glad to assist you.
Thanks & Regards
Ravi Kumar Microsoft Support.