I'd scan as Grif notes at the next link -> http://forums.cnet.com/5208-6122_102-0.html?messageID=3250454&tag=mncol;lst;1#
Any number of malware from keyloggers to others can cause this.
My 6 year old desktop (HP with vista) started some ago to have problems with the keyboard: even typing with most attention and pressure on keys, it randomly skips some letters. I just bought a new keyboard but the problem does not seem to be resolved. A computer tech I called told me it probably depends from the PC itself and he has to clean and reinstall all sw in order to make it work! Of course the cost would be prohibitive (as buying a new cpu!) and I have an hard time to believe the guy. Did anyone of you ever bumped in a similar problem and found a solution?? Thank you in advance for your help! Sorry if my English is not right ...
Franco (Rome - Italy)