DSON creates temporary files when active (they have a unique identifier in the name). Somehow these can no longer be found at the location where they are supposed to be

Possible reasons:

The "writeable" runtime is not writeable (happens when you install the runtime in Program files when using Windows Vista,7,8. Mac would be a runtime without write privilges)

You removed the writeable runtime from Poser

You moved files around (different location)

You installed new morphs in genesis

You deleted the temp files

That's all I can think of now