Okay, so I am having the exact same problem as someone else in this forum, but his thread has been closed,
Basically, completely out of the blue XGUI has stopped working, I haven't changed anything, just started the server and bang.
"ulx menu" is now returning invalid command
and if I try saying "!menu" then I just get:
[@ulib\client\cl_util.lua:9] Received bad RPC, invalid function (xgui.toggle)!
He mentions some update posted by Stickly Man, but that guy posts so often I cannot find it anywhere... help?