Workgroup PCs not showing up in Explorer after SP2 Upgrade

I am running a small network as a workgroup with 4 XP Pro and one MCE 2005
computers. Since I upgraded the XP machines to SP2, I started intermittantly
losing sight of some of them when browsing the network from the other PCs.
It became a problem with the MCE 2005 machine because MC will not let me add
a PC to the My Video list that is not visible in the Entire Network view of
the network. I am running the SP2 firewall and share folders containing the
videos. I can access the invisible machines when I type out the UNC name,
but they will sometimes not allow me to find them when I browse the network.
Any idea what causes this?

I do not have the source KB article number in front of me ... but it is
documented in the Msoft knowledge base articles. Do not remember the fix they
said.

"Reactor Phil" wrote:

I am running a small network as a workgroup with 4 XP Pro and one MCE 2005
computers. Since I upgraded the XP machines to SP2, I started intermittantly
losing sight of some of them when browsing the network from the other PCs.
It became a problem with the MCE 2005 machine because MC will not let me add
a PC to the My Video list that is not visible in the Entire Network view of
the network. I am running the SP2 firewall and share folders containing the
videos. I can access the invisible machines when I type out the UNC name,
but they will sometimes not allow me to find them when I browse the network.
Any idea what causes this?