Sorry I couldn't reply sooner...
If you have not wiped your system and reinstalled from scratch, there is a possible solution which would not require you to have to start from the beginning and lose your data - it's called an "inplace restore" of Windows XP.
Basically, its a way to start with a clean operating system and NOT have to reinstall everything else or lose your user settings. You use this option when you can NOT boot to the desktop to use system restore and "Last Known Good" fails to bring you any joy.
What you do is boot from the Windows XP CD exactly as you would if you were installing for the first time and bypass the recovery console option. Accept the XP license agreement by pressing F8 and make sure that your current copy of Windows XP is highlighted and press "R" to repair it.
What happens when you do this is similar to "rolling back" to an earlier version of XP, you'll have to download and reinstall all of the updates and service packs issued after the version you reverted to - but your user settings and data stay behind.
Before you do this:
- Go to the Microsoft Support Website and read the following KB Instructions: http://support.microsoft.com/kb/315341
- Be sure to pay strict attention to the information about "Method 2" - Starting from the Windows XP CD
- Do NOT install to any folder other than your existing XP installation if you want to preserve you existing user settings.
- Do NOT format your drive under any circumstances. If you are asked to format your drive, ABORT the installation. If this happens you either chose to install a "clean" version of XP or you have a problem with the integrity of your hard drive and we will have to troubleshoot further to get you up and running.
When finished you should have a clean load of all original (read "pre-updates applied" here) XP files in the installation folder and you build it back to where you were.
If you're not sure or you have more questions, ask BEFORE you do anything. I have performed this procedure on my own computers and for my customers more than 30 times with great results.