This just happened the first time I ever tried the slots in the casino. After that it worked. The dark grey one with (I think) "Gruesome" in the name, in the double row in the middle. I got an error message of some sort (and this was over a week ago, I sent an in game PM to Ghost but not sure he got it) when I went to exit the gump. I think I clicked on the Cash Out button but not sure, just wanted out and don't think I saw a good exit option... I had not actually played and I don't recall if I went to the ATM gump or not. Sorry but that PM to Ghost had better detail as the incident was fresh in my mind.
Ok so the error message was something like "This machine is over it's credit limit". When I tried to get out I get a bank check for 427,207 gp or similar. I still have it in my bank box, maybe in the gold bag in there if a GM can get in and take it back.
Q