Concerning lens compatibility, some M42 lenses have extra pins that are designed to engage with non-standard features used on some lenses. Some Fuji lenses have a plastic pin on the aperture ring to enable open-aperture metering. This doesn't interfere with mounting the lens on non-Fuji cameras (or at least, I've successfully mounted my one such Fuji lens on my Zenit E), but I've heard that schemes used by some others do cause problems. I don't know if that was the source of the problem you report, katabatic, but it might be.

I've run into something that could be similar with K-mount lenses (or at least Tamron Adaptall adapters) intended for Ricoh cameras. These have little metal pins to provide an electrical connection between lens and body, but these contacts jam in screws for the lens mount of every non-Ricoh camera I use. The solution in this case is to use some clear tape to cover the offending screws. The pin doesn't engage with enough force to rip through the tape, so this does the trick.