Well the caveate to moving items in your libraries is that Poser itself will sometimes write Absolute file paths when you resave things to your libraries and if you move those items you will break them. Your best bet is to always check new saves in a text editor and change absolute paths to relative paths. IE:
C:Poser ContentPoser 6RuntimeLibrariesCharacterBorisFilename.cr2
Should be edited to look like this:
:Runtime:Libraries:Character:Boris:Filename.cr2