Basic router issue

I know this is a basic issue - I am just over thinking this.

Cisco 2621 - FastEthernet 0/1 = 172.21.1.1
XP laptop connected to above port via x-over cable.
XP Laptop IP addr = 172.21.1.4

Can ping the router from the laptop
Can telnet ssh into router from laptop
Can not ping the laptop from the router telnet ssh session

Do you have the Windows firewall or other firewall software enabled on your computer?

I second jtartist's question. A firewall in windows is a very possible scenario for pings from the router not to work.