Can't make a LAN server

I'm trying to make my own listen server but I keep getting this error.

Host_Error: UserMsg: Not Present on Client 97

I've tried removing the ClientRegistry.blob, checked liblist.gam etc. and all sorts of stuff, but I quite frankly don't know how to fix it. I've had this problem for a very long time now, and I haven't cared about it that much since I can jump in publics too, but I think its time to get the server fixed!

All the problems started occuring after I downloaded a huge map pack that contained hundreds of maps, I placed all the files where they belonged and then I got "svc_bad" when I made a server - the bug came before the server itself was even ON. I didn't try to fix it back then but now I no longer get the svc_bad-error, instead its the Host_Error: UserMsg: Not Present on Client 97 that haunts me now.

So... if anyone knows how to solve this little puzzle, please feel free to help me out. I've done some personal records in publics/friends servers but the demos are blatantly useless for any submission to anywhere since they aren't done in LAN.

Thanks in advance!