I'm using an 8core Mac Pro, 24Gb ram, Fusion, Intel PRO NIC ..
and I have about 30 different VMs, of which I like to have about 3-6
running at any one time. I have them all set up in bridged mode. I can
usually get 3 or 4 running simultaneously... but often after that, vm's
that I fire up will just not work (browsers cant display web page etc)
Occasionally I am able to get a new vm running, maybe by closing old
ones, rebooting, repairing net connections.. I really don't know if
what I do helps or its just luck that I get it working... once I even
uninstalled the NIC adapter in the vm.. rebooted.. and it worked!
Usually though I give up after messing with it for half an hour...
Sometimes, i'll come back to it later without touching anything and lo! it's working..!
I have no idea wha is going on.
it's a real problem...
What's your network topology? If for example you're at home and going through a router, the router might be configured to only give out a certain number of IP addresses.
Does networking work if you use NAT mode?
Are your virtual machines set to use static or dynamic IP addresses? Are any of them copies of others?