My hunter team never used to do this, but now they do. They're the only team that does.
One or two slaves (non-active toons) will occasionally run off into the distance.
My priests, druids, shamans or mixed teams don't have this behavior which is really odd.

I'm using Keyclone and the Jamba addon.
I'm using Party1 assist method.

Basically run along (mouse movement on main, other toons on auto follow).
Have disabled Jamba's strobe following, because I sometimes don't want auto follow to engage on its own.
My toons get to where I want them, I target something and click my attack macro.
Macro is the standard BM hunter... Auto Shot, Steady Shot, Kill Command, Hide UI Errors... macro, from Elitistjerks.com.

Most of the time they stand there and alternate auto shot-steady shot (one of each sequentially per keypress) and attempt to activate Kill Command (once per keypress).
Rarely, one or two of them will start to auto run, in a random direction.
They were stationary, but still on auto follow when this occurs.
There is nothing like: pressing forward key, press shoot macro, forward run key is stuck on...

It has me stumped.