One of the IT guys at work was telling me that he had one version of XP he was installing get probed and infected the first time he hooked up to the internet, while he was trying to download the security patches after a clean install.
I've run into several web pages at home on my Mac that try to install dialers and spyware. Since they're exe files they don't have any affect on my system, but I keep my beebers on full stune anytime I'm at a site I'm not familiar with, anyway.
1) XP is way, way better than 98, in my experience. with 98 I had about 1 crash per 4-6 hours of usage.
2) If your computer is shutting down during you ad-aware scan, I'd almost guarantee that you're infected with malware. You may need more expert help than I can offer; but here are some things to try-
3)on the ad-aware settings, make it do a scan on computer start-up, then restart your computer instead of going straight to doing a scan. Maybe your adaware can do its scanning b4 the malware is started up. On a related note, you could go into msconfig (Start to run, type in msconfig) and set your computer to safe mode, and try and run a scan from the safe mode. It may be that your current install of ad-aware has been compromised, and maybe you should reinstall it after doing the next step.
4) use spybot search and destroy. Crucial. Probably you should do this first. Spybot S&D might fix enough problems for Ad-Aware to begin working. If that's the case, alternate running one and then the other over and over until it looks like you're clean. Make sure you've updated both programs, and keep updating them over the next several weeks, b/c it may be that your malware is a new variant that can be mostly solved right now, but may leave some remnants that will only cleaned up with subsequent updates of those programs.
5) Look on the internet and find out what you might have and get some more details. Has your homepage been changed? Do a search on that home page, and go down lood for websites that talk about being hi-jacked to that website. Go back to your Norton scans that told you that you have spyware and write down specifically the details of what is says you might have, then go on the internet (using a different computer or Firefox) and search up info on that. If you try and use IE, while infected, it will be useless. You could also do some searching under "malware" or "spyware" and see if you can identify which program or type of program is doing the damage.
6) you could try and do a system restore to some point when you know your computer worked. (this might be a good starting point, but I'm not sure)
7) Post more details. It might allow someone to identify the malware you have. (For example, a common one changes your homepage to coolwebsearch.com)
8) Don't swear too much. Good luck- that'a about as much as I know, but I'll look forward to hearing updates on your progress and seeing what others might offer in the way of help.