computer reboots

My computer simply reboots at random times. I was told this could've been caused by a virus from a while back. I have an emachines, with Windows XP. I've run AdAware, Norton Anti-Virus, AVG Anti-virus, and I use SpyBot and Zone Alarm. Nothing as far as viruses shows up whenever I run a scan. Upon rebooting, I get a message that says "system has recovered from a serious error", and SpyBot asks if I want to allow the change to delete "kernelfaultcheck". I've said yes to allow that change, but it doesn't matter. Even after I get these messages, until I do a system restore to a few days back, it still reboots every 3 minutes or so, sometimes not that long between. At first I thought it was only when I attempted to open Explorer, but it's done it even when I've not been connected to the net (have DSL). It's gotten to the point where every day I have to do a system restore at least once, sometimes more. Occasionally, I can go a couple days between restoring. I've installed the lastest updates offered by Windows. I've also run Stinger, and nothing was found. I ran hijack this and saved a copy of the log file created, but it's all Greek to me. Please help!!!!!

 

I'm afraid I don't know what you're talking about by running online scans and safe mode. I've only run the downloaded versions of those programs I mentioned, and haven't run anything from being online. I also haven't run all of the tutorials on here. I don't know where to find them. A friend just suggested I might be able to get help here, and I'm still trying to figure out my way around the site.