Are you using auto resize anchors or Sliding and Visibility settings to get your objects to slide?
And just to be sure, you are previewing the layout by selecting Preview Mode for the layout?
This is a kinda silly thing to ask, but do you have a printer driver installed on your WIndows system?
Yes, using Top and Left anchors, fields are sliding and visibility for certain fields is set to "hide when printing."
Yes, selecting Preview Mode (not a custom button...)
The machines acting up are the client's machines, so I will have to check on the printer driver issue. But, they certainly can print from these machines...doesn't that suggest installed drivers? (I don't know as much about PC's as Macs.)
Do the above settings work differently for Mac & PC?
There have been some issues with sliding in FileMaker 12, but those issues have not been reported as being specific to Windows: http://forums.filemaker.com/posts/ea146d9cec?start=1&stop=10#189429
On the other hand, I have, on very rare occasions, seen cases where file or layout corruption produced problems on one platform that were not observable on the other. You might create a small, brand new test file with sliding fields to see if it exhibits the same issue or not.