Back to Rogue :) Anybody have an opinion about Snobs and Lightning Walls?

[lyyn]

Overall, Lurkers are very nice people

So I noticed
Still, hearing some war stories would be fun.

But I'll take what I can get and settle for telling mine

Here is a recurring one:
Here I am, standing in front of a door, firing at a mob on the other side. The situation is well under control until...
…my char decides to run headlong into the room.
This is killing me. Really, it is.
It always happens the same way: I'm holding the shift key and firing. At the start, the mob is big, so there is always one bad guy or another in focus. When the mob is thinned out and no one is in a straight line to the door anymore, the focus is lost. That is when, sometimes, my rogue runs into the remaining mob.
Against, say, Goat Archers this is survivable, against Poison Spitters, not so much...
Had it only happened once, I would have shrugged it off and thought I was clumsy enough to let go of the shift key. But this is happening twice or so per game. It isn't a Hellfire issue, because it happens in Diablo too.
I have tried to link this to me moving the mouse to focus on a new target, or maybe just to the amount of time that the shift key is pressed, but since it only happens once in while, I can't really pinpoint it to one cause. Plus, right after that happens, I'm usually REALLY busy and not contemplating some technical issue

Has this ever happened to anybody else? Or do I just need a new keyboard?