I've had an MCE for Lord of the Rings Online (copied and modified from the World of Warcraft one) working on one computer. I moved it over to another machine with a dual-screen setup on Windows 7, and when windowed or full-screen, it seems to repeatedly place the boundaries where the mouse can move/can't move in the wrong place. Re-centering the mouse changes where the boundaries are, but seems to lock them to the top-left corner of the screen instead of to the actual position of the window in windowed mode. Switching to freelook (with the right upper trigger) seems to move the boundaries in some manner that I can't figure out.
MCE is attached - please let me know if anyone has an idea why this might be happening.