Thanks for the tip about the compatible version of sysinternals procmon. This place must have been the only site I forgot to search for it on! The version at filehippo is still there and launches nicely on win2k One hint of trouble I did notice about my MPC install was that it included a local copy of D3DX9_41.dll. As this seemed odd, i renamed it to take it out of the picture. It felt as if this improved things but the 0xc0000142 then reappeared. I think it only happens for certain media file type(s) or even certain files. I just tried it with the compatible ProcessExplorer running, and can't find a file to break it at the moment.... Have to see what files I can find. Good tip with the re-registering dlls. Funny how one forgets these old tricks sometimes. I'll try that now too.