Look for a (a file that lists correct checksums) from the official MAME source or community databases like No-Intro or Redump (note: No-Intro focuses on consoles, but MAME has its own DATs). Use a ROM manager (see below) to audit any set you find.
In a Split Set, files are divided between Parents and Clones. Mame Full Set Roms
MAME is struggling with CPU performance. Go to Video Options and enable "Throttle" or reduce audio sample rate to 22050Hz. Look for a (a file that lists correct
If you use MAME 0.264 but have a ROM set from 2015, many games will fail to load many games will fail to load