Try a Windows Rollback... Goto Start HELP and click Undo changes to your computer with System Restore. Pick the last system restore point before you made the errors.
You could do what I often do.
IF you want to REALLY learn how XP runs, this is how you go about doing it, and dont mind spending a few days... do this... It will take awhile, as you learn the aspects of the computer (DCOM, Registry, System Tasks, Startup Tasks, etc)
Go into the event log, its in administration under control panel. Look at the errors that are on the sheet. Then go through each one working with google and yahoo (sometimes you get the answer easy on Yahoo and not Google). Solve each one.
First you need to sort out the system issues, then you got to find out if the application errors in the log are fixed due to the system issues.
If you cant fix one problem, move onto the next, and come back to it later. Then after all this is done, you shouldnt have any system problems, then clear the System Log and Application log, restart, and check for Application Errors...
I usually clear the system log and the Application log, during this process, a few times... so that I know what is coming up, and to help me find out what is the order of things.
When you get Ctrl Alt Delete up, go through each process and search it on google. Find out what it does. If you want MORE information, download Windows Defender, goto advanced, and their is a system explorer in there... I think thats what its called... You can learn even more from that...
Mike