I have had the issue that after suspending a certain VM the disk activity would go up after a few minutes. Quite annoying because the system was almost unusable. Kind of like it was doing some defragmentation. After a few minutes of researching (a.k.a googling ) I came across this thread on the VMWare user forums which explained that you had to edit the .vmx file and add following three lines:

mainMem.useNamedFile = "FALSE"
mainMem.partialLazySave = "FALSE"
mainMem.partialLazyRestore = "FALSE"

This did the trick for me.