I stumbled on this board when searching for a good link to send a friend and thought I'd share that worked for me. I've had installation problems with SP2 in the past until we found out that SP2 has a built-in firewall. If you are running a third party firewall (eg McAfee, etc.) you should disable it during the SP2 installation. Once you've installed SP2 (and haven't run into any other install problems) you should be able to go into your Control Panel and disable the Windows Firewall. Then go back and activate your regular firewall. This is just a suggestion and shouldn't be regarded as a fix. This is just what I've had to do when we ran into XP not booting up or locking up when installing SP2. All PCs running XP Pro with the SP2 installed after knowing this have been updated with no problems. Hope this helps.