It's not uncommon. The only way of fixing it is, as far as I know, to restart Poser.

It often happens when you've had Poser running for a long time without restarting it, it's like Poser gets tired and starts to nod off (sounds insane, but well.. Poser is a weird program in many ways L)

USUALLY the file can be saved and reopened without ill effects after the restart :) You could save a copy of your figure here to the Figures palette so you have a spare - but a simple restart usually fixes this (a reboot of the computer is a good idea, too to make sure you have freed up any memory-blocks that have gone "off")

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You just can't put the words "Poserites" and "happy" in the same sentence - didn't you know that? LaurieA
  Using Poser since 2002. Currently at Version 11.1 - Win 10.