A few weeks ago my computer kind of had a snapping sound and the screen flickered. Ever since that time it has run slow, locks up, takes forever to come on, takes forever to go to the web. When I tried to log on to my AOL account a visa verification screen came up and ask me to verify who I was and to enter my credit card number and ATM PIN. Of course I didn't do this but it did the same thing on another web site. I have run scan after scan with stopzilla and then Norton but it says things are fine. I dont know what to do or what to use to get rid of whatever is there.