Can you open them in safe mode?
To get to safe mode:
Reboot.
After the POST(the memory check and the *beep*) start tapping on the F8 key.
You should get a boot menu.
Choose #3 safe mode.
Try to open them there.
If you can... there is something running that is interfering with your ability to open your documents in normal mode. While in safe mode:
Go to start>>run>>msconfig.
Choose selective startup.
Take the check out of load startup group items.
Click apply>>ok>> and reboot normally when prompted.
Can you open your documents now in normal mode without anything running?
If you cannot open your documents in safe mode... can you copy them to a different location and open them?:
Right click on something you need to open.
Choose Copy.
Go to a clean area of your desktop.
Choose paste.
Now try to open it.
Did it open?