Icon pictures have been changing on their own (mp3 icons changing to notepad, etc). Sound quit working on one speaker until I reinstalled the sound driver, half the files in my firewall disappeared and it had to be reinstalled. When I opened up my pictures folder, suddenly everything in it vanished-- tried to save another picture to it, it also vanished. I've been having frequent moments when the computer suddenly freezes for 10 seconds or more, and for no apparent reason. Norton and Panda Scan say there is no virus, McAfee found QHOSTS and deleted it (although it doesn't fit the symptoms described), and Housecall says I have no virus. I did sfc \scannow, I ran checkdisk, I've done everything I can think of. I'm begging anyone reading this, please help me.

Have you tested you memory? run a test there could be a problem with your Ram.

How do I test my memory? By the way, I had a hijack attempt several weeks ago. My homepage was switched to a male organ enlargement site and I had four or five new places in my favorites menu (the male organ site was one of them). At the time of the attack, I had one pop-up appear after another-- I had my firewall up at the time. I got out of the situation by restarting my computer. Don't know if that is important or not.

I found a place called PC Pitstop and tested online. Everything checked out except my hard drive, which it says has a "minor problem". This takes me back to my original theory something is wrong with my hard drive.

I'd for safety sake buy new ram and install it and watch

http://www.memtest86.com/#display this site may do it, have not tried it, as I just seached on google.
Bad ram will cause deletion of files and error messages that seem unconnected to memory, also try hijackthis and spybot. many computer users prefer and hope it is a virus, as hardware costs, it is usualy ram, on one machine I had a similar problem and ignored ram, it eventualy burnt the ram port on the motherboard, which cost even more.

I'd like to thank the both of you for your responses. Yes, I agree, it sounds like it could be a memory problem. From what I've read though, to start from the Memtest86 boot disk, I'll first need to change the settings in Bios, only I have no idea how to get there, or what to type. Could anybody tell me? Sorry. I know I ask a lot of questions, but I'm not very good when comes to computers.

Found the new Memtest86 ISO, burned to CD, and it ran perfectly. Definately not a memory problem. I ran the test for eight hours without a single error. After following more good advice I heard on this site, everything seems to be running smoothly, although I plan on keeping my fingers crossed. Thanks Thatbloke and EC.