Windows Firewall shuts itself down..why ??

Just about every second restart of my system my windows firewall is shutdown
and i dont seem to know why. I did a log for the firewall to see whats going
on and out of all the messages that are all the same this is the only thing
that stands out of it -2004-12-19 07:53:09 OPEN-INBOUND UDP 00.0.00.00
000.000.0.00 0000 0000 ..i placed all the zeros to hide the address but my
question is that the OPEN-INBOUND UDP was the only time thats showed up on
the entire log, i started the log after the the firewall shut down last time
and checked it when it happened again. So what is it thats causeing my
firewall to shut itself down ? Maybe i have a Virus or something ? I ran a
virus scan with Norton System Works and came up with nothing and tryed all
manner of Spyware scanning software and still came up with nothing. So if
there is anyone that can give me some info as to whats going on here and how
to make it stop i would greatly appreciate it.

Thanks