In order to install SP2 successfully the system must be free of malware.
Can you boot in safe mode?
See if you can uninstall SP2 and then start hunting for the malware that is probably present in the computer although if there are no data files you care about saving, and no programs that you cannot just reinstall you can do a fresh installation of XP which will cure all problems (except for hardware problems).
Once you do the reformat and fresh install you can install all the updates.
The Win XP firewall was not on by default until SP2, so before you connect to the internet turn it on.
Then install whatever Anti-virus application you want to use.
The AVG freeware ap is excellent and there are several other freeware AV aps as well as commercial aps, but choose one and install and update it asap.
The next ap which should be installed is Adaware SE freeware (but no longer offered on the Lavalys site, at least I couldn't find it yesterday, so get it from Major Geeks which hopefully still works)http://www.majorgeeks.com/download506.html
Then Spybot Search and Destroyhttp://www.safer-networking.org/en/index.html
Be sure to enable “Teatimer” which gives you realtime protection
I would also recommend installing Microsoft Defender, the replacement upgrade for the Microsoft Anti-Spyware beta which was just released this week. It also provides realtime protection.
Edited by Enthusiast, 17 February 2006 - 04:33 PM.