Known OpenSolaris 2009.06 Guest Issues (System Administration Guide: Virtualization Using the Solaris Operating System)

System Administration Guide: Virtualization Using the Solaris Operating System

Known OpenSolaris 2009.06 Guest Issues

If you are running an OpenSolaris 2009.06 HVM guest on Hyper-V SP2 (RC build), you'll need to update your OpenSolaris 2009.06 to at least snv_113to get the fix for CR 6768204, “dnet interface takes a long time to resume after plumb/unplumb in Hyper-V virtual machine.” Without the update, the network interface doesn't work for several minutes after the first interface unplumb/plumb operation. Obtain the update from the OpenSolaris Packaging Repository .
If you're running an OpenSolaris 2009.06 HVM guest on OpenSolaris 2009.06 dom0, you'll need to apply the workaround for CR 6828707 for XServer to start on the guest.

The issue is how long gdm should wait before it assumes a started Xserver is defunct. The default set in /usr/share/gdm/factory-defaults.conf is:
GdmXserverTimeout=10
The default should be increased. To override the default and set the timeout to the recommended value, add the following to /etc/X11/gdm/custom.conf:
GdmXserverTimeout=30
If the workaround is not used, the user will not see the GUI login window. If booted in text mode, only a console login window will be available. If booted in graphics mode, only the OpenSolaris startup screen will be seen.