APC on media temple dv 3.5
Its quite sad that forums.mediatemple.net is not indexed by google.
The initial steps to install APC are mentioned on a lot of blogs. But none of them mentioned the 500 errors and the error log saying nothing more than “premature end of script headers”.
I finally found the solution on forums.mediatemple.net (from this link posted there) which basically says that you have to enable APC for each site individually and work with modifying the apc.shm_size to stop fragmentation from happenning which causes the 500 errors.