If the following applies to you:

A) ProTools works fine.
B) Booting DP up under MAS works fine and running Direct I/O gives me playback.
C) When I switch to DAE, everything 'seems' to work until I quit DP. When I try to reboot DP under DAE, my system keeps freezing:

Do this:

1) Within the DAE folder find the Plug Ins folder.
2) Remove each and every third party plug-in (i.e. NOT stock DAE plug-ins).
3) Boot up Digital Performer under DAE. Does it boot?
4) Assuming it does, quit DP, put one of the plug-ins back into the plug-in folder within the DAE folder. Boot DP.
5) Repeat until you find the problem plug-in.
6) Contact the appropriate manufacturer.