"Missing ROM/CHD files" error. Solution: The pack says "6000 ROMs." If you are missing one, it's likely a CHD (Compressed Hunks of Data - hard drive image for games like Killer Instinct or NFL Blitz). Search specifically for the CHD set to match your ROM version.

Sound is crackling. Solution: In MAME Plus, go to Audio Settings > Increase "Audio Latency" to 2.0 or enable "Sync to Refresh Rate."

Game runs too fast / too slow. Solution: This is usually a VSync issue. In Video Options, set "Triple Buffering" On and "Wait for Vertical Sync" On.