ClassFactory cannot supply requested class 0x80040111 Error: -2147221231

Using Visual Studio 2008 I first encountered this when trying to open a standard save file dialog box in visual basic. So far I've worked around it after fruitless searching. Now I find that any action which would cause a save/open dialog (eg. ctrl-O) also fails. I've searched more and still don't know how to fix it.

Stuff I do know: It's not a Visual Studio error, it apparently can occur in any number of other applications (which is why searching for it is annoying)

It's either .NET or COM related, I tried reinstalling all of .NET with no luck, and I've never mucked around with COM ever, I don't really even know what it is.

Something is missing, misplaced, or it could be DLL version issues.

I really don't want to deal with uninstalling VS2008, or MS Office (as one result I found suggested) or any other big application.

So, somebody, somewhere is trying to CoCreate some object that it (thinks) it needs to do its job. This may or may not be a Visual Studio object. Since it manifests in the Save / Open dialog it could very well be a shell object.

The most likely explanation is the registry entry for the object has been corrupted in some way, or the dll that exports the object is corrupted in some way. For the latter it could be missing completely, or just in a bad state for some reason.

One thing you can try doing is running regsvr32 on likely candidate DLLs, but that's just shooting in the dark.

Another, more advanced option is to attach a debugger (such as ntsd or windbg) to the Visual Studio process it self and set a breakpoint on CoCreateInstance() in the system dll (make sure to look up its exact signature in the header file—it may be #defined to something else). Then get the GUID for the object that it is passing as the argument to CoCreateInstance(). Looking this up in your registry (or a friends registry that doesn't have this issue) should give you a good idea of what DLL you need to go mess with.