Im having the same issue with Mame Plus! Extended 141u4. I tried both x64 and x86 versions on my Windows 7 x64, both had same issue.
I'm currently running MameUI64 with no issues at all, other than it being a massive memory HOG.
The get the error in Mame Plus! Extended when you either right click a game or try to run a game.
This is the error when I try to run a game. It seems to be a Microsoft Virtual C Runtime error.
Problem signature:
Problem Event Name: APPCRASH
Application Name: mamepuiXT_x64.exe
Application Version: 0.141.4.0
Application Timestamp: 4d976c4d
Fault Module Name: msvcrt.dll
Fault Module Version: 7.0.7600.16385
Fault Module Timestamp: 4a5bdfbe
Exception Code: c0000005
Exception Offset: 0000000000015ba1
OS Version: 6.1.7601.2.1.0.256.1
Locale ID: 1033
Additional Information 1: 9046
Additional Information 2: 90463e8d30578953898131694ebfbb23
Additional Information 3: f187
Additional Information 4: f187c9f899f2f10e8104f14f503d4ba1
After the crash, I always have to rescan for available games as it shows 0 when I restart after crash.