Been trying to uninstall SP 3 because of a compatibility issue with a program I'm trying to run, but I get the message "The system cannot find the file specified," followed by one that tells me that the removal couldn't be completed. Without it telling me which file it's looking for, I'm not sure what to do. Any suggestions?

Thanks.

Are you using Add or Remove Programs? / Control Panel?

http://support.microsoft.com/kb/950249

Yes, I used the removal program from Add/Remove Programs in the Control Panel. The message comes when it seems to be near the end of the installation process.

I would try the other options in the above link.

If none of that works try reinstalling first.

Just tried reinstalling but still got the same message when uninstalling. Already saw the link above and tried those options.

So you tried removing via the Recovery Console?

Have you tried removing in Safe Mode?

There are a few ideas in this thread:

Cannot Uninstall XP SP3 RC2 in order to install SP3 : Windows XP Service Pack 3 (SP3) : Windows XP IT Pro : Microsoft TechNet Forums

If you do edit the registry back it up first. ERUNT is good for that:

ERUNT and NTREGOPT

How do I create the log they're talking about?

It should be created automatically:

C:\WINDOWS\$NtServicePackUninstall$\spuninst\spuni nst.inf and %windir%\spuninst.log

Did you try Safe Mode?

Did you try the Recovery Console?