Try;
1. Click Start, and click Run
2. Type MsConfig and press Enter
3. Click Expand File
4. On the File to restore text box, type url.dll
5. On the Restore from text box, specify the position of the Windows XP CD
6. On the Save files in text box, browse to "C:\windows\system32" Note: I assume your system drive is C and your system folder is windows. ** Yours may be at WINNT **
7. Click Expand
8. Restart your computer