There is obviously something wrong with your floor segments. Were they made by union labor? We might be able to find enough users with this problem to start a class action suit, but first...
Please provide more info:
FPSC Version
Default or custom segments/entities
System specs including video adapter
Whatever else you can think of they could be related to the issue?
I've seen this once in a while with some models and it usually turns out to be a mesh problem, but never with any and all models like you stated.
Brian.