Explorer.exe uses 50% CPU, and Windows Explorer won't launch

Well, I'm running XP SP1 +all updates, 2.4Ghz P4, 1GB RAM, Norton Antivirus and Internet Security 2004. Everything starts up nice, seems to work like it should. But when I try to start Windows Explorer, it won't launch, and explorer.exe goes to 50% cpu usage. Goes a little down if another prosess uses alot of cpu, but it comes back to 50%, nothing more or less, and no explorer starts. But I can browse my files through Nero's browser, and everything is just fine, or with cmd. I tried to start internet explorer, that works, and then i added the button for showing folders in IE, but then both iexplore.exe and explorer.exe goes to 50% cpu usage each, but it shows me my files and lets me do what I want in explorer through IE. explorer.exe is just normal when doing this. I noticed that some keyboard shortcuts didn't work, like ctrl+c for copy, or pressing Del or F2 for renaming and so on. I had to right-click with my mouse and select my action there, that worked... If I shut down explorer.exe, and restarts it again, it's normal, but when trying to open windows explorer, nothing launches, it just uses 50% cpu again. I've tried different virusscanners, spyware-removers, trojan-removers and so on, and I found something that I removed, but it hasn't solved my problem. I', beginning to get pretty frustrated here, someone that can help?