Video driver crashes when multi-boxing

[declensions]

Hi guys, hoping to get some good help here.

I am multiboxing 10 diablo 3 clients using VMware, with 1 VM per client, all running on the lowest settings possible.

The problem I am running into is that every few hours my GPU driver will crash, and all of the VM screens will go black. I end up having to restart all the VM's because I can't do anything when the screen is black. (Just the VM screens are black)

• I have tried 2 different GPU's, an nvidia GTX 460 and a radeon 5850 (both 1gb) and get the same problem.
• I did not have this problem when I was running the bots on the Intel HD 4000 graphics (when I did not have a dedicated GPU). I wanted to take stress off the CPU so I installed a dedicated GPU

I think it may be a ram issue, since the intel HD 4000 shares the system's ram. Does having multiple VM guests count as having multiple displays?
Will I be able to fix this issue if I upgrade to a 2gb video card?

I need to make this work using VMware (in otherwords, 1 ip per client) so please do not suggest that I use isboxer unless there is a way to do the same. Your help is greatly appreciated.

My system specs:

gigabyte z77
i7 3770k (not overclocked)
OCZ vertex 4 ssd (120gb)
32 GB ram 1333
xfx radeon 5850 1GB
rosewill 650w PSU