Try this:
Check if your "Sticky Keys" is turned "On", turn it "Off":
1. Go to the Control Panel.
2. Double clcik "Ease of Access"
3. Under "Make your computer easier to use" click on "Make the keyboard easier to use"
4. Under "Make it easier to type" click to uncheck the box before "Turn on sticky keys" to uncheck it.
5. Click on "Apply" and ""Save"
I would also suggest using an online virus scanner such as
TrendMicro Housecall.
If you have a virus, and your anti-virus was bypassed by the intelligent virus, then it is best to use an outside virus scanner. Also check for worms and Trojans. Other options is to make sure your remote desktop is turned off, and possible printer sharing.
Edit: Sorry, I forgot to ask what operating system you are using, since navigation through various Windows OS's can be different.