Originally Posted by Sean
There is another possibility. If I recall correctly, you use a Mamiya M645 Super. Is there any chance that you left the dark slide in place?
I know there is an interlock which is supposed to prevent you from releasing the shutter or winding the film if the dark slide is in place, but I have one Mamiya 645 insert that is defective - you can load film on to it, and advance the film through the camera with it, but something is wrong with the gearing or the connection, and as a result, the dark slide interlock doesn't do its job. It lets me merrily shoot a whole roll, and the only clue is that the advance is a bit noisier than usual.
I have other 120 and 220 inserts, and they work fine in that back. If I switch the problem insert to another back, the new back exhibits the same problem. I haven't tried the problem insert on all three of my camera bodies (I probably should) but its pretty clear that the insert is the problem.
I would check the insert, and the dark slide.
Hope this helps,