Sometimes if XP is installed on a HD with HD errors and/or malware, the files will be corupted and cause all sorts of problems.
Did you "prep" the HD by running malware scans and/or formating it, and running chkdsk prior to the New Install ?
If not, and since it is a new Installation, I think that might be your best bet.
You could try running "sfc /scannow" from the Start>Run command box. That *might* work.