Your "guid" is a Globally Unique Identifier set by Punkbuster. If you do not have a CD-Key then no guid will be given. Do you have a valid CD-Key? If so you might want to try deleting your cdkey file and reentering it. But remember to run Quake3 manually so it opens in baseq, instead of say using a gamebrowser.

If your still having problems after that I would suggest try manually running PB Setup

GL