What is a worker process?

When we log in to sql server (NT), we have a couple of process id's
which
always lock up. If we kill the process, the next user to log in and get
the
process id will lock up. Sybase Central calles the process a WORKER
PROCESS.

We have tried to stop and start the server, and even completely
rebooting
the machine, but it only changes which id's become bad.

Any help?