"The emulator crashes on startup." Fix: The compression corrupted the header. Try converting the CSO back to ISO using the same tool. If it fails, the download is bad.
While many sites claim to offer "10MB highly compressed" files, many of these are unreliable or contain malware. Stick to well-known community hubs for the safest experience:
If you own original discs and want compressed backups, these sources are commonly used in emulation communities:
A command-line tool (part of the MAME project) that converts ISOs to the highly efficient .chd format.
Be cautious of sites claiming to offer "Highly Compressed PS2 Games" (e.g., a 4 GB game in a 10 MB file).
Right-click your ISO and select Add to archive > GZIP with Ultra compression .