Many utility programs view registered programs

[Mike Doty]

RegDllView is really nice.
You can see what is registered on your system and unregister with a right click menu. I was having problems with an OCX and found that it was
registered in another folder! Great utility.
I'll check out the many, many others when I have time.

Many other useful programs.
http://www.nirsoft.net/utils/index.html

[Chris Boss]

This utility I found on the same site some time ago was a life saver:

http://www.nirsoft.net/utils/shexview.html

This program displays all the Shell extensions loaded in Windows. You can disable them too using it.

I had a problem where a number of programs were crashing when the open file dialog was used, in particular graphic programs. Most don't realize that third parties can extend these dialog (and other parts of Windows) via the the shell in windows.

It turns out a shell extension was behaving badly and once I disabled it, everything was fixed.

Third party shell extensions can wreak havoc to windows applications.