If your BearShare has been sitting unused for awhile it's cache of addresses to
connect to will have gone stale. Shut down BearShare if it's running, download
connect.zip and unzip it into the folder called "C:\Program Files\BearShare\db"
and then start your Bear up again.

If that doesn't work, grab BearDiag, use it to generate a full report and bring it to
the original BearShare experts at Technutopia.