Error Code 5: Incompatible menu file...
There are two potential causes of this error.
Problem A
You didn't uninstall an old version of SkyUI before upgrading to 3.0 or newer.
Solution A
Make sure you really removed all traces of older SkyUI versions, then install the new version again.
Installing SkyUI with the Nexus Mod Manager can help you with that, because it will detect and list conflicting files from SkyUI 2.2 and 3.1-alpha.