Problem with 2-way Remote Desktop Control

Hello,
My problem is that I cannot control my desktop PC with my laptop.
They are both connected through a LAN cross cable, and more or less easily recognize each other with Map Network Drive.
I have recently installed Symantec's PCAnywhere on both computers, and while I'm able to control my laptop with the desktop smoothly, the only way to do this vice versa (Laptop as the Remote client, Desktop as server/ host) is by submitting an active "call remote" (or invitation?) from the desktop to the laptop. It wouldn't recognise it otherwise and report as "could not find computer".
I have WinXP Home build 2600 on both the desktop and laptop.
Do you think it has to do with activating any service? I tried tweaking with them and activate services that seemed relevant, but my laptop will still play "blind" and wont trace the desktop.
BTW: Pinging desktop->laptop works great, under 1 ms, but laptop->desktop, 4 requests timed out.
Thank you for your help

Do you have a firewall installed on the desktop - such as ZoneAlarm or Internet Connection Firewall (ICF)? Try disabling this. You can disable ICF by right-clicking the Local Area Connection is Network Connections and selecting properties. Click the Advanced tab and check the ICF is not enabled.