Okay, that can be caused by a variety of things.  The first thing to try is go to Edit -> General Preferences -> Misc tab and uncheck Use Binary Morph Targets, if it is enabled.  Poser does not do very much "sanity checking" of data on read and write, and the "out of memory" message it gives can often be misleading.  If disabling that option allows you to open an old scene file you may be able to recover at least some of the data in it.

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