How to associate a program with a given extension?

[m^2]

So if i understand correctly i should be able to view files with ext. ".djvu" in TCUP using F3 button or with XnView? I tried both and both times got the error message saying "Format of this file could not be determined". What am I doing wrong?

Thank you.

P.S. Using Vista here.

What program do you get this message from? WinDjvu?

iso files used to open in tcup
i installed poweriso which had the iso's opening in it
i disassoiated iso file in poweriso but still cannot open in tcup

wtf happened?

help

PowerISO broke TC UP associations and when you removed theirs - there was nobody to restore ours. I'm affraid you need to run the installer once again.