Contra hangs every time I play it

[jharris]

I was wondering if anyone could help me figure this one out. Most of the time when I play the game Contra it freezes. Empirically speaking about 8 out of 10 times. It usually hangs on two spots. One is at the end of level 1, right after your character enters the base. The other place is after beating the boss at the end of the second base (level four). Of these two, the latter is the one that happens more often. This are the things that I tried:

* Tried the game on MAME 0.80, 0.99, 0.106 and 0.126.
* Tried getting an updated set for each MAME version.
* Tried using both bootleg and US set 1.
* Tried different difficulty settings.

Nothing I've tried seems to fix it. At first I thought getting an updated set would solve it but that didn't work. MAWS info for Contra reports the bug, but I wonder if anyone else has experienced it as bad as I have. I surely don't remember the original game freezing like that. What else can I try? Maybe a DIP switch setting?