Sometimes when I do something that would cause an autosave (loot a chest, pick up a feather, accept a mission), the game silently quits, no errors messages or anything. My PC has a quadcore CPU.
This is a known issue with AC2 running on multicore CPUs. If you suffer from this bug, you need to set the game's CPU affinity to limit it to 2 cores. To do so, open the task manager after launching the game, find
AssassinsCreedIIGame.exe in the task manager's processes tab right click it, click on Set affinity and uncheck all but 2 items in the list.
You can also launch the game with the correct affinity settings set every time by creating a custom shortcut. Make a shortcut to
AssassinsCreedIIGame.exe, then edit its target to be
C:\Windows\System32\cmd.exe /c start /affinity 5 AssassinsCreedIIGame.exe (/affinity 5 sets CPU affinity to CPU 0 + CPU 2).
If the issue persists, or if you are encountering it on a dualcore system, you can set CPU affinity to only 1 core; in this case replace
/affinity 5 with
/affinity 1 or
/affinity 2 in your shortcut if you choose to make one.