It looks like it crashed at 11pm (when the backup runs) and then i have rebooted it at 12:35am, during this time there was 0 disk and network activity (there should be a lot i was syncing a 6gb mailbox to a remote office) however cpu activity is quite high around 50 - 75%
I am using ESXi 4.1.0 build 348481 and the intel E1000 network adapter
windows logs just go dead, nothing and they all start again when the machine is rebooted, not a lot to go on! and the frustrating thing is the rest of the VMs are fine, i can login and have a look, no problems (although issues retriving files etc as the sbs11 box is the DC and file server as well)