Paralells 4 won't work with Leopard network accounts

I have been trying to upgrade all our accounting machines from parallels 3 to 4 for better performance, but even with the new builds we keep on having the same issue and have gone back to version 3.

After upgrading to parallels 4 with 3 different machines (mac mini, 2 imacs) it upgrades fine and everything works ok. When I log off the network account and try and log back in, I get the leopard server message "you are unable to log in to the user account "useraccount" at this time. Logging in the the account failed because an error occurred"

I then will login as the local admin and unbind the server using the directory utility and rebind. Then when I login to the network account is sometimes works, but after log off and logging in again, I get the same error message everytime for the network user account.

We have never got this message before until we tried to upgrade to parallels 4, as soon as I remove parallels 4 and rebuild the computer from an earlier disk image with parallels 3, the problem goes away.

The recent case was on an Mac Mini with 1 GB RAM, running 10.5.6 trying to upgrade to build 4.0.3810. Bootcamp is not running on any machines, and we are running leopard server 10.5.6

Thanks