Tonyhax International -> PS2s and 80 Minute CD-Rs
The earliest PS2 console models (SCPH-10000-SCPH-39004) have a hardware bug that causes some games to either not boot at all, or crash after boot, while in-game when burned to an 80 minute/700MB CD-R. On PS1 consoles, the same 80 minute/700MB CD-R has no such issues. The only way previously known to work around this PS2 hardware bug was to instead burn an affected game to either a 74 minute/650MB or a 71 minute/620MB CD-R. Since this is a hardware-level issue, this affects all mod-chips and soft-mods. Even if you pressed your on PSX CD-ROM in an 80 minute density, it would effecct that too.
Tonyhax International as of v1.5.4 now has a software-based fix that ensures 80 minute CD-Rs boot correctly. This fix is only applicable while Tonyhax International is reading the 80 minute CD-R. It can't do anything after the game starts, since the game takes over control. Since the PS2 hardware bug can still potentionally lock up the game during a disc seek/read after the game is booted, the only 100% solution to completely prevent the issue is to first patch the disc image with my psx80mp patcher.