QUOTE(egga @ Dec 1 2008, 05:17 PM)

I have reinstall the windows. It's normal at first, I can copy paste as usual and run the windows task manager. But once I install Oblivion, the problem back. I reinstall windows again and not install Oblivion. It works fine. then I install 7z. that I got from internet, it's back again. Should I purchase a new Operating System? Or should I purchase a new Hard Disk?Oh the problem is getting worse. I can't view JPEG file and cannot run regedit. Is this some kind of virus?
Thank you...
Egga,
which version of Windows is that? We might need more references to help you.
I assume it's either XP (most likely with Service Pack 2 or 3 installed) or Vista, such as Home Premium.
It sounds weird enough in fact. Is the desktop intact? Make sure there isn't a fake one layered over the real stuff (couple trojans use this trick). Also, do you have some form of antivirus/antispyware control?
Just to make sure, try out some detection/disinfection tools. Two rather straightforward ones are RogueRemover and Stinger. If you need an antivirus, get one ASAP - your computer should stay protected at all times; better yet, take in account a firewall to replace Windows' own if you're running lower than XP Service Pack 3.
If the registry editor isn't working, try installing alternatives such as RegSeeker and HiJackThis! (this one isn't very immediate to use, but it's often very useful).