I am having trouble getting a connection (ping, with eventual desire to map a
drive) between two machines on XP SP2 - before upgrading to XP SP2 I did not
have this problem.

Here's my set up...
Two laptops with XP SP2, connected via a router. When logging into the
"local machine" on both laptops, neither machine can PING the other. Same
story when I login to both machines on the same domain... what gives.

I know the IP addresses of both machines, subnet mask and such - but I can't
reach one machine from the other... I need help - can someone throw me a bone?