>Hi All,
>
>I encoutered a weird error while running the setup.exe of my application on a user machine.
>
>Usually the setup runs fine, but one user got the following error
>message while installing the local portion of the software.
>
>I made sure no other application was running when he installed
>before posting this message.
>
>The setup program returned:
>
> COMCAT.DLL unable to register itself in the registry...
>

I just ran into this error with a system that had VS 6.0 installed before installing SP4; there was a problem with the date/time stamp on the copy of COMCAT.DLL that I was trying to install.

COMCAT can't simply be copied into place and registered; it's one of the commoninterface .DLLs that Windows loads up almost instantly. It must be installed using the Setup API or a similar mechanism that delays the final copy and registration until Windows restarts. Installing it by hand requires that you do something along the following lines:

(1) Copy the new version of COMCAT.DLL to the system in a directory other than the Windows System directory and register it with REGSVR32. Restart Windows. When Windows restarts, the registry will point to the new COMCAT, so that you can delete and replace the copy in the Windows System directory.

(2) After Windows restarts, copy the new version of COMCAT.DLL into the Windows System directory and register it there. After Windows restarts again, you can delete the copy outside the Windows System directory.

You're better off letting an install product like InstallShield or the Setup Wizard which uses the Setup API to do delayed replacement and registration handle the task for you.

Be aware that there are a lot of OCXs that are dependent on COMCAT; until a current version is in place, many OCXs like ASCTRLS.OCX and DAXCTLE.OCX will not register.

>
>Anybody has seen this error before?
>
>Or anybody can tell me what is this COMCAT.DLL used for?
>
>It sounds like a communication DLL but I am not sure...knowing what it
>does could probably help me out pin-pointing the source of the error...
>
>Thanks a lot folks!
>
>Pascal