i uninstalled service pack3 for XP. When I tried to restart the computer a blue screen came up and said
: c000021a (Fatal System Error)
i would like to know how to fix this
i have tried opening in safe mode and Last Known Good Config and nothing worked.
i do not have the xp disk to do a restore and i do not what to do a restore. if there was a way to do a recovy with out being able to log on that would be great.

..hi there!..i think you just destroyed your registry in your OS..better to repair or reformat your PC at all..borrow XP installer from your friend or anyone that is close to you..don't forget to back up your datas..i hope it helps!..^_^..

A Problem... look, you are going to have to get a Recovery Console of some sort. Cannot you borrow an XP cd?
No? Then perhaps you can download one of these and burn it to a cd [unzip if necessary, then burn the .iso, don't open it!]:

Use the cd to boot your sys into the RC. I think then you could try again to uninstall SP3... its uninstall files may exist still. It is possible that one or more of the replacement files did not copy correctly.
Anyway, in the RC, enter these commands:

cd %systemroot%\$NtServicePackUninstall$\spuninst
batch spuninst.txt

My brother inlaw took a look at it and ran a repair with the xp cd. It found some things but didn't fix it. Then he did some kind of scan on it (not sure exactly what he used)and found something like 2200 problems on it. He repaired them and the number went down to about 500 when he scanned it again. He scanned it about 5 times before he got down to 0. Now it works fine.

Thanks for your advice though guys