In seamless mode left or right click on mouse moves mouse pointer vertically.

I am having an issue that pops up randomly.  When I move my mouse to another (secondary) computer's desktop in "seamless" mode, the mouse pointer moves appropriately, but if I left click anywhere on the screen, the mouse pointer moves vertically and then performs the click at some point while the mouse pointer moves vertically.  If I move the secondary computer to another position on the grid, so that it is above, below, or to the right of my primary computer, the issue appears to go away.

Goofing around with some settings i have found that choosing to have the inactive screen darkened fixes the issue.  However, I like to view one screen while working on another, so this isn't really a viable option.

Restarting my primary computer fixes the issue, but it soon pops back up again.

Some background information:  I use a laptop as my primary computer and I routinely switch between a wired and wireless network connection due to me moving around the work area with the laptop.  The laptop also routinely goes to sleep when I transport it around the office.