Vista losing connection to XP machine

Hi All!

Just got a new Vista Ultimate machine. I have an old XP Home machine that I
wanted to use to create a simple home network. I created a workgroup on both
machines (Workgroup). I created a username that was the same for both PCs
(same passwords as well). I connected both machines to my router via
Ethernet. I first had a problem with my Vista machine not seeing my XP
machine. I fixed that by installing the LLTD on the XP machine. After that,
I could see the XP machine in the Vista network map, but could not connect to
it. I discovered that my Norton firewall was blocking it. I turned off the
firewall and viola... I was able to see each machine from the other and
access both.

Here is my problem:

I have my XP machine setup with user names and passwords for the whole
family. (Kids can wreak havoc on a computer if they know even the smallest
amount about them) On my administrator account, I have set a password
protected screen saver so the kids can not get onto my administrator account
if I happen to be logged on and am not around. I have noticed that whenever
the screen saver kicks in, my Vista machine is no longer able to connect to
the XP machine. No error messages, but when I try to access it through
explorer, It does not even appear. Internet works fine on both even after the
loss of the network on the Vista machine.

Logging back into the XP machine allows Vista to "re-establish" the
connection after a few minutes. At least this is as best I can determine is
happening. I could be completely wrong though!

Does anyone know how to resolve this? It seems it should work as XP Pro
does... if the machine is on, you can access it on the network even if it is
not logged in.

It's not a huge deal right now as the computers are right next to each
other, but it will become a pain when they are in seperate rooms!

I am not a network guru, so if anyone can help, I would appreciate it!

Thanks!