Suddenly old patches wont open, but newly created patches will?

I'm running Max v5.0.8 (40057) on Windows XP. When I try to open an existing patch, Max just freezes, no messages in the Max window, just a complete lockup. If I create a new patch, then it works fine and I can reopen it no problem.
The weird thing is I tryed to update Max to a more recent version about three months ago, and the exact same thing happened. I never fixed it but when I reinstalled the older version things went back to normal. Now, all of a sudden its happening with this version.
Seems like some kind of external dependency but I'm completely stumped as to whats causing it. Patches load up in Runtime no problem which again is weird.
Any ideas or help would be greatly appreciated!