I agree with Darren. This is effectively the same approach we posted earlier in the thread.
Of all the computers we have tried so far we have never managed to resolve the issue by simply unregistering and then registering the file. Sometimes it works if youunregister the file, log off (a reboot is not necessary), log on and then register the file.
However, the one method that always works is that described by Darren.
I would recommend this approach (complicated as it appears) to anyone for whom the simple re-register doesn't work.
We send a batch file and an old version of mscomctl.ocx to the affected users and get them to run the bach file (it may need to be run as an administrator). The batch file we us is:
if exist %systemroot%\SysWOW64\cscript.exe goto 64
%systemroot%\system32\regsvr32 /u mscomctl.ocx
rename %systemroot%\system32\MSCOMCTL.OCX MSCOMCTL.SAFE
copy .\MSCOMCTL.OCX %systemroot%\system32\MSCOMCTL.OCX
%systemroot%\system32\regsvr32 mscomctl.ocx
%systemroot%\system32\regsvr32 /u mscomctl.ocx
del %systemroot%\system32\MSCOMCTL.OCX
rename %systemroot%\system32\MSCOMCTL.SAFE MSCOMCTL.OCX
%systemroot%\system32\regsvr32 mscomctl.ocx
exit
:64
%systemroot%\sysWOW64\regsvr32 /u mscomctl.ocx
rename %systemroot%\sysWOW64\MSCOMCTL.OCX MSCOMCTL.SAFE
copy .\MSCOMCTL.OCX %systemroot%\sysWOW64\MSCOMCTL.OCX
%systemroot%\sysWOW64\regsvr32 mscomctl.ocx
%systemroot%\sysWOW64\regsvr32 /u mscomctl.ocx
del %systemroot%\sysWOW64\MSCOMCTL.OCX
rename %systemroot%\sysWOW64\MSCOMCTL.SAFE MSCOMCTL.OCX
%systemroot%\sysWOW64\regsvr32 mscomctl.ocx
exit