Sorry to post spam, but did you try running the server with JUST ULX/ULib and URM? Was it still broken?
It may be that it started breaking when you added URM, but it could be something colliding with URM that just happens to break XGUI as collateral damage. Since URM hooks into XGUI so closely, it's possible that even if URM isn't broken, if something is incompatible with it, that it might break XGUI.
Just to be double sure, you might try running URM with only ULX/ULib and nothing else.