Window-Switching Issue

Hello,
I've been having an issue where, after switching windows while playing GW, my NPCs seem to "warp" around rather than walk or run. If I use mouse-clicks to move around, like the NPCs, my character will "warp" to those points instead of actually running there. Again, it's only after switching windows from GW then back again that this problem arises, and it usually resolves itself within a few minutes (though is still very annoying). Can anyone offer any help?
Thanks.