Hello Philip,
Welcome to Microsoft Community Forum.
I can understand the feeling of performing an action and it does something else. I will be glad to assist you.
- Did you make any specific change in the computer prior to the issue?
The issue may be caused by any third part software conflict. I would suggest you to perform clean boot and check if the issue still persists.
Putting your system in Clean Boot state helps in identifying if any third party applications or startup items are causing the issue. You need to follow the steps from the article mentioned below to perform a Clean Boot.
Refer to the link to perform clean boot.
How to perform a clean boot in Windows
http://support.microsoft.com/kb/929135/en-us
Note: Refer "How to reset the computer to start normally after clean boot troubleshooting" to reset the computer to start as normal after troubleshooting.
I would also suggest you to check the keyboard settings.
Please refer to the article: How to use the United States-International keyboard layout in Windows 7, in Windows Vista, and in Windows XP
http://support.microsoft.com/kb/306560/en-us
Also, check if the issue is reproduced using On-screen keyboard.
Please refer to: Type without using the keyboard (On-Screen Keyboard)
http://windows.microsoft.com/en-us/windows/type-without-keyboard#type-without-keyboard=windows-7
Hope this information is helpful. Please do let us know the result, we’ll be glad to assist you.
Thank you.