Errors with Windows XP

I have just bought an new external hard drive and in moving some files around
I think I have accidentally moved some I shouldn't have - particulalry those
relating to the "My Documents" folder. Some may also be due to the fact that
I have incorrectly deleted some files.

As a result, on startup, I now get errors relating to the failure to install
programs like:
- nxzhpmm.exe
- mm_try.exe
- ldpdkek.exe
- ypager.exe

I would appreciate it if someone could advise the best course of action.
.