Microsoft SBS 2011 VMware Workstation Constant Crashing?

We have a Windows 7 Host running VMware Workstation with 5 virtual machines, One Windows server, 2 Windows 7 machines and 2 Windows XP machines.The host and non server VM's are fine, they run 100% of the time and never have problems, my SBS 2011 VM is another story. There have been nothing but crashe's over the past 6 months and they are fairly random.I beleive the server BSOD's and then it reboots, upon rebooting it just sits at a black loading windows screen forever until you completely power it off and then back on, at which time it boots up normally.The BSOD's happen ususaly around 12 AM when Windows server backup runs and creates a server backup on another server over the network, the backup runs 7 days a week but we only see the BSOD about twice a month.I have run through drivers in my SBS 2011 install and all seem up to date to me.