This type of bugcheck is pointing towards memory corruption. I think you will need to test the RAM by physically removing one stick at a time and seeing if the problems are associated with one or other of the modules.
[code]CHKIMG_EXTENSION: !chkimg -lo 50 -db !win32kbase
2 errors : !win32kbase (ffffce25d23a9482-ffffce25d23a9bba)
ffffce25d23a9480 17 48 *cb 49 40 44 8d 4d 7a 44 8d 45 0f 4c 89 78 .H.I@D.MzD.E.L.x
...
ffffce25d23a9bb0 0c f5 05 00 66 39 71 48 74 1a *4a 8b 49 40 41 b9 ....f9qHt.J.I@A.
MODULE_NAME: memory_corruption
FAILURE_ID_HASH_STRING: km:memory_corruption_stride[/code]
