I had this problem a awhile ago in some servers where i was getting kicked almost instantly and the reason was always PB failure - pb heartbeats failure.
I google it and in many forums including evenbalance forum there was no precise answer.. i got answers like unistall ET, close firewall etc..
Today I fixed the prob. After some time reading my cfg file i turned two numbers to 0 and it did the trick for me.
So I put: set r_ati_fsaa_samples "0" and set r_ati_trueform_tess "0"
If you got this problem in any server try these.