Frank,
You can try unofficial Parallels Flags. They are present in Parallels Desktop 5.0.9308 and there could be issues with Parallels desktop 4.0 or previous builds of Parallels Desktop. It is not guaranteed to work and complicated, but here are them:
open config.pvs of the virtual machine (located inside .pvm-bundle of Virtual Machine) in TextEdit
find the segment in .xml code: <NetworkAdapter>
and input next options:
<NetworkAdapter>
...
<ForceHostMacAddress>1</ForceHostMacAddress>
<DHCPUseHostMac>0</DHCPUseHostMac>
...
</NetworkAdapter>
if the problem still persist after this then try to enable both options:
<NetworkAdapter>
...
<ForceHostMacAddress>1</ForceHostMacAddress>
<DHCPUseHostMac>1</DHCPUseHostMac>
...
</NetworkAdapter>
Last edited: Jan 17, 2010