Windows 8.1 guest consumes all host memory and then hangs Max

Hi,

Updated to latest VMWare Fusion 6 update, on 32gb RAM iMac, running Mac OS X 10.9.2.

Had noticed that at times when running the Windows 8.1 guest the iMac had frozen, requiring power off to reset.

Have a Windows 8.1 64bit guest that has max memory set at 8gb.

Started the Windows 8.1 guest and run up OS X Activity monitor to watch memory usage.

Started a backup and the host RAM get chewed up in no time, way beyond the physical limit I had set.

Eventually, consumes all the memory and the iMac freezes.

Do not understand why the max physical limit I set is being ignored.

Is there some setting that I can prevent all this memory being used and then freezing the iMac?  BTW, not running Unity

Hope someone can assist please, as currently the Windows 8.1 guest is useless given it keeps freezing the iMac when all memory is consumed!

Thanks

Peter