Frustrating issue with ESXi 5.1 and SBS2011

[BFABen]

The OS itself is installed and operates as I would expect it to - however, every hour to 6 hours the network stops working on JUST that VM.  The system will say that it can't find the router, and the rest of the network suffers (no internet access, the Sharepoint site stops working, the VPN won't accept connections, etc)

I swapped out the physical NIC already (was using an onboard which was a Realtek 8111F and I discovered some compatibility issues with VMs so I installed a dual NIC with an Intel chipset certified for use on ESXi) but the problem persists. 

I found an article online a few minutes ago that says the e1000 VMNIC has issues with SBS2011 and that if we switch it to the VMXNet3 the problems would go away, but I hesitate to make too many changes and not get anywhere. 

The BPA tool can't find anything wrong with the server, so the configuration is sound.  More recently I've disabled DHCP on the SBS server and moved it to the router, but it's not been long enough to determine if that will help fix the issue or not.

Any ideas? 

[BFABen]

I went ahead and changed the NIC to the vmxnet3 adapter but it caused the network and sharing center to lock up the system.  Instead, I installed vmxnet 2 (enhanced) and it went right into the network properties page.  I re-assigned the IP information and applied the changes.  So now, as usual, the system is working fine (for now). 

Still would welcome feedback from fellow SBS2011/ESXi 5.1 users

[BFABen]

Well, I don't know what happened, but the entire host became unresponsive around 4am this morning.  Can't get to the site at the moment, but this thing is really trying my patience.

Other than the ONE VM misbehaving, I think I get it fixed and now the whole darn host goes offline (can't ping it, can't remote into it using vSphere, nada)

I'm trying not to flip out until I figure out if someone yanked the power cord on accident...