Here are a few things to try :-
1. Download this little fix click here
2. Start, Run and type “sfc /scannow” (not the quotes but the space) and have your WinXP CD ready to put in the drive, should it be wanted. If the main Windows set-up screen appears and covers the progress bar, just close it. SFC will exit with no closing dialogue. To see which files. if any, were replaced look in Event Viewer. If SFC doesn’t work, the RPC locator service needs to be started in Start, All Programs, Administrative Tools, Services.
3. Find the hidden file ie.inf which is in the Windows\Inf folder. Right click the ie.inf file and choose Install from the menu that appears. Restart the computer after the files are copied.
4. To repair Internet Explorer 6 on a WinXP SP2 system, Start, Run, type "iexplore /rereg" (not the quotes but the space). It will re-register the DLLs.