Been having problems since I installed latest XP security patches earlier this week. Tried to do a repair install, it gets to the screen where it's going to install, thes says:
Warning
setup failed to remove product catalog SP1.CAT
warning
setup failed to remove the product catalog DXBDA.CAT
warning
the setup failed to remove ...(same as above)
DXXP.CAT
dxxp.cat
dxxp.cat

Warning
The signature file for XP Professional upgrade is invalid. the error code is fffffc06
The system annot find message text for message OXfffffc06 in the message file for systsetup.dll
Setup failed to install product catalogs. This is a fatal error. The setup logs should contain more information.

Suggestions pleaseeeeeeeeeeeeeeeeeeeee. Thanks

Does the unit run?

If it does, I would rescan it at Windows Update and then try to reinstall the corrupted patch.

Call M$ and tell them what happened and you need help. They have never charged me for help when repairing a bad download. Just tell them you checked the box that ask if you wanted to always trust Microsoft.

mia: these links address your errors;

http://support.microsoft.com/?kbid=307153

http://support.microsoft.com/?kbid=823303

http://www.vbulletin.com/forum/showthread.php?t=107148