Time for the weekly MAME update: get MAME 0.125u7 over at the Source Updates page. I anticipate a u8 next week followed shortly thereafter with MAME 0.126, so now would be a great time to verify that there are no showstoppers in any games you care about!
An important note about this release: inclusion of debugging support in MAME is no longer optional. That is, you can still disable it (using the -nodebug option, or setting 'debug' to 0 in your mame.ini file), but you can no longer compile without it. This will give a small-ish performance hit (under 5% in most cases) in exchange for always being able to pull up the debugger and will reduce the test matrix necessary to verify MAME's behavior.
Note that due to a slight oversight, the debugger is enabled by default in this build, so you may need to explicitly turn it off. This will default to off in u8.