Try pressing P, it may be paused. If that doesn't do it check out the forums on the FMS web site.
I've runs this on 5 different computers running windows 95, 98, 98SE and XP and haven't experenced any problems at all.

I am using FMS Version 2.0 Aplha 8.5 and models designed for this version will not work on the older versions and this model requires Version 2.0 Alpha 8.5.