You can also try this before rebuilding your XP machine:
To resolve the issue, perform the following:
Ensure that the correct Internet Time server is selected.
Go to Control Panel, Date and Time, Internet Time, and ensure that the server address is correct to which your PC is synchronizing. If the issue is not with the Internet Time server, perform the following:
Go to command prompt. (Ensure that you have logged in as an Administrator)
Execute the following commands in the same sequence:
net stop w32time
net start w32time
Restart Windows operating system.
Not sure if this will fix your problem but I grabbed it from:http://support.microsoft.com/kb/555440/en-us
Edit: Also you can find the hotfix here:http://support.microsoft.com/hotfix/KBHotfix.aspx?kbnum=951531&kbln=en-us
You will need to select your language. You might want to try this out too before you re-install everything.
It may not work, but hopefully if it does will save you some time.