I'm developing a game and it's currently in playtesting. The last version, v0.5, worked perfectly for all playtesters (about 10 to 20 people).
The next and current version, v0.6, works perfectly for me and for several playtesters, but three of them experienced problems: one has it soft crash (it freezes, but doesn't crash the computer) randomly with seemingly no pattern, and two others have it hard crash (it crashes their computer entirely), and in a consistently repeatable place -- however, that place is *different* for those two (one is when he starts a stage, the other is when a countdown preparation part of a stage reaches 0). I've asked all three of the people it crashes on for their system and driver etc. specs, and can find nothing in common.
Now, I'm not asking this as a technical question, obviously you'd have to know far more about the game than I mention here in order to help with that. What I'm asking is a more general question: when you are confronted with situations like this, where a game has a problem on several computers but you don't have access to any computer it has problems on, what exactly can you do? Do you try to solve it remotely? Do you try to gain access to a computer that it crashes?
What I probably need to do is send them v0.51, v0.52, v0.53 and so on and see at which point the crashes were introduced, narrowing it down to particular changes I made, but that will take awhile, and it would be annoying to them -- they're doing me a favor by playtesting it and I'd be asking them to repeatedly try something which they know will crash their computer.