
PS2s have some issues when booting certain games. In short, in PS1 mode the GPU is emulated using the EE, and this EE applies some per-game patches. As tonyhax uses an unsanctioned way of loading games, the EE is never told it needs to load new settings for the new game, and thus the old one's settings might not be fully compatible.I just finished going through all my legit US/Jpn import disks with Tonyhax on my PS2... there were two that wouldn't boot at all (NTSC-U Xenogears, and NTSC-J Bust a Move, aka Bust a Groove), and one that hangs on a loading screen (NTSC-J Einhander). Just goes to show that even some legit disks are problematic.
I thought it was very strange that Bust a Move wouldn't run when I'd had no problems running it's sequel (which I was never able to do on my modded PS1 due to its modchip detection).
On a side note; I've corrected (for the most part) the resolution issues I was having by running GSM and setting output mode to PS1 NTSC @60hz. While it screws up the browser (making launching my Cool Boarders 4 entrypoint awkward), it sorts out the resolution of any NTSC PS1 game I launch with Tonyhax... with a few exceptions... NTSC-U Vagrant Story has an odd resolution for it's title screen, so you can't see any of the selections, and NTSC-J Dead or Alive seems to line double in game - seemingly an interlace vs progressive issue.

Yeah, I found that.PS2s have some issues when booting certain games. In short, in PS1 mode the GPU is emulated using the EE, and this EE applies some per-game patches. As tonyhax uses an unsanctioned way of loading games, the EE is never told it needs to load new settings for the new game, and thus the old one's settings might not be fully compatible.
That also affects the video issues. In fact, if you try with tonyhax v1.3.1 it's highly likely you are gonna experience the same issues, even though tonyhax v1.3.1 uses the exact video settings a stock PS1 BIOS uses, and thus leaves the game with the video settings it's expecting as if had been booted through the BIOS.
