No guarantee but it's worth trying one or more of these :-
1. To repair Internet Explorer 6 on an SP2 system, run "iexplore /rereg" (not the quotes but the space). It will re-register the DLLs.
2. To repair IE, Start, Run and type in "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.
3. In SP2 only, change the boot.ini file. The easiest way is via Control Panel, System, Advanced, Click the Settings button under Startup and Recovery. Now the Edit button under System Startup and change /NoExecute=OptIn to /NoExecute=AlwaysOff. Save the boot.ini file and OK your way out. Reboot the computer. It is completely reversible by changing the boot.ini file back to the original.