explorer.exe freezing PC after right-click on .htm files ?

to be revised

 

XP SP3 explorer.exe freezes (hour-glass) the PC (need to shut down and restart) when right-click on an .htm file to view 'Properties' etc.
Doesnt seem to happen with other files (txt files, etc) or folders.
And, there is no error message/s.
Same thing happens when try to use menu bar File and Edit/Cut button.
Does not happen in ‘Safe Mode’ !
Is there a way to 'repair' (ie maybe reinstall etc) explorer.exe without needing to do a complete 'XP Repair Install' etc ?
Avast, MyBB, CCleaner, SUPERAntiSpyware, sfc /scannow, chkdsk c: /f/r, and System Restore (no points available) have all been run.
Also tried ShellExView, but very cautiously since not that familiar with its workings.
Haven’t installed anything lately.
Thoughts ?