it is possable that you have a keyloger on your computer like back orafice,the only way to get to your cookies is to have access to your system files, if you are useing windows xp it can't be done with a trojen.look for a file that is installing back orafice. forgot what file it it but you can get the info on it by doing a search for back orafice..don't confuse it with back office witch windows uses if you have office..
might not help but its in that area where your problem is at..btw it can be downloaded to your computer through a pcture..heres a link to check out
http://www.bo2k.com/news.shtml