Hitting enter key before last page finishes gets locked up

I originally posted this in networking but now i feel this could be a Window XP problem.... I have 2 CPU's.. One running Vista (The new System) my other is XP The XP system is on a wireless network. My Vista system has the modem and router running comcast cable network. I use a 802.11b Ma111.b netgear adapter to communicate. While on the internet on the XP system sometimes my screen take awhile to completely finish.. If i then hit the enter key to select something on the unfinished screen my task will just sit there spinning or in some type of loop or waiting on something because it will not respond anymore yet i can start another task ok...... Anybody heard of this type of problem? Does it sound like a XP software problem? thanks.... Allan