XP SP1 Networking Problem

[Guest]

I have recently reinstalled Windows XP Pro (SP1) and have the following
problem:

Just after logging in, explorer.exe starts to connect to various IP (they
seem to be random) at port 445(microsoft-ds). As you can imagine, system's
performance goes way down.
My temporary solution for this is blocking all outgoing traffic for
explorer.exe and TCP port 445, and manually restarting explorer.exe proccess,
after which the problem is gone.

My system has all updates except SP2. Also, my computer is not a domain
member although there is one in my network.

Any ideas what might be wrong?

 

[Bob]

ports 445 and 137-139 are for file and printer sharing - if you have a
standalone box, you should definitely block those, but if you have a home
network, then don't. (But don't let those ports be open to the big, bad
internet....)

 

[Guest]

That's all true, but my 445 port is closed (even stealthed), that's remote
445 port explorer is is connecting to. It sends SYN_REQ packets to random IPs
at _remote_ TCP port 445.

I heard that SMB protocol, apart from its usual function for sharing files,
is also used in domain's AD service and for propagating group security
policies - but does it have anything to do with my situation, since i'm not
in a domain?