Regarding your settings I'm wondering why you need so much PermSize?
So I would recommend to set the MaxPermSize to 256m and also to decrease
-Xmx to 1024m. Try to load/parse the heapdump again... Normally these
settings work for all 32 bit heap dumps...
If you don't want to change your settings, I would recommend to download a
separate RCP of MAT and try to parse your dump with this separate
installation of MAT. (Here you have additionally the possibilty to parse
the heap dump within the command shell with: "ParseHeapDump.bat <path to
dump>".)