I have a similar problem in my 7.2+w2k, but the problem gone with my 7.2+wxp. When I encountered this problem at w2k, I will close some of the applications and rerun the synthesis, then the process will be done without error. To some rare extreme cases, I need to reboot the PC and start the synthesis without running any other apps.
I think that may be due to runing out of some resources, as this workaround is working for my environment all the time, I don't look into deeper about the real cause and neither do I contact syn city as suggested in the error msg.
ntxp.