When a PS3 game boots there are 3 types of external files that could make it crash
The savegames
All (or most) games generates a savegame automatically the first time you boot the game, this savegame is intended to store the game settings. Additionally some games creates another savegame automatically for the user progress
Well... if the game was mounted with incorrect settings or have some damaged/invalid files te game crashes at that first boot, and sometimes the savegames gets corrupted
So... the next time you try to boot the game (with same settings or different) it loads the corrupted savegames and crashes
The gamedata installation
This installation happens also the first time you boot the game, sometimes the installed gamedata gets corrupted too, is not usual to happen but it could become corrupt too
*The game updates are installed "on top" of the gamedata installation, so messing around with game updates (as example installing them in a incorrect order) could damage the gamedata
The trophy installation
This is also generated the first time the game boots (and loaded everytime the game boots), is very rare but sometimes this trophy installation could become corrupt too
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So incase of weird problems (like the ones you are having) you should try to delete all this files to allow to the game to make a "fresh boot" (without loading external files)
In that "fresh boot" the game should create all this i mentioned (savedatas, gamedata, trophy)
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If the game refuses to boot after you check all i said... you should start thinking if the game files are damaged/corrupted/modifyed/fixed
Nowadays you dont need to modify any game files, is better to keep the original game files
If you want to check if your files are identical to the files inside the real bluray disc you can perform a hash check by using the IRD file of the game, you can download IRD files here:
http://jonnysp.bplaced.net/
Search for your game using the TITLE_ID (as example BLUS12345), download the IRD for it and use one of the tools that supports IRD to check your files
*Managunz support IRD files and can do this check (but is better to make the IRD checks in PC because the processor of a PC uses to be faster than the processor of a PS3)