This actually applies to seemingly all source games. Basically, I'll be strafing or walking forward and moving my cursor to aim at something when it suddenly seems interrupted and stops. It'll only continue moving after a split second or when I re-move the mouse. It's kinda hard to describe, but basically it's like the mouse is pausing on the screen at small, random intervals. The problem just appeared out of nowhere. I've played on this laptop (it's a Dell M1530) for a while with no problems. I searched the steam forums with no avail. I don't see the mouse issue in any other games outside the source engine. It seems to occur when I'm holding down a key more often then it does when I'm just moving the mouse. Not sure if it's hardware because I've interchanged mouses, plugged them into different USB ports, etc. Honestly, I think it's my keyboard, but that's just a worry of mine (since it's a laptop :-/) EDIT: Further testing shows that it occurs when holding down a key or moving, not when moving the mouse. Still not sure it's the keyboard, but if it is how would I tell Dell about this?