port 135 RPC problem

Hi,

I got this message from my sygate firewall.

“generic host process for win32 services (svchost) is being contacted from a remote machine using local port 135 EPMAP location service dynamically assign ports for RPC do you want to allow this program to access the network”

had it before reinstallation of XP, and had problems with it. (blaster alike problems, but Norton couldn't detect a virus.)

in the meanwhile i installed service pack 2, use shot the messenger (http://grc.com/stm/ShootTheMessenger.htm) and
norton antivirus still can't find any virus.

But i still see a lot of attempts from a remote address to connect to port 135, [LOG]:
16-9-2004 19:52:45 Blocked 10 Incoming TCP 81.70.207.184 01-00-20-00-01-00 1939 81.70.27.42 00-00-01-00-00-00 135 C:\WINDOWS\system32\svchost.exe Normal 1 16-9-2004 19:51:39 16-9-2004 19:51:39 GUI%GUICONFIG#SRULE@APPCONFIG-BLOCK#C:\WINDOWS\System32\svchost.exe

I'm blocking them with my firewall.

Does that mean i'm still vulnerable? and how can I protect myself even better?

Thanks a lot,
Jarra