I don't know what causes it, but after a while, all programs installed to the AppData will stop launching. as far as I can see, they doesn't show up in Task Manager's processes tab at all after I open them. they just won't open.
like I said, this only happens after a few hours of using Windows, the programs launch fine after first booting. the only way I can seem to fix it is to reboot, but that's only temporary.
and some apps don't support being installed for all users in Program Files, so that's not an option.
Windows 7 x64 SP1