I have a Dell Optiplex PC with an i5 CPU and 16GBs RAM, with 3 monitors. Recently added the 3rd. View Sonic, Dell, Dell monitors. Everything seems to work ok except when moving excel, word or Google Chrome to the middle monitor. After you move excel over, you cannot left click on a cell or type in it. However I can right click all over the place. If I move the excel window back to any other monitor all the keys I typed suddenly appear. Move it back to middle, locked again. Same thing happens with Google Chrome when doing a Google search. The weird thing is if I move Internet Explorer, Windows Explorer one of our business programs to the middle monitor it types in the search bar just fine.
The setup uses 3 VGA monitors. One is directly connected to the PC with VGA cable, 1 is connected with Dell DP2VGA adapter and the problem child is connected with startech USB2VGAE3. We've unplugged the startech adapter, uninstalled the startech software, rebooted, and reinstalled the software. Same problem. We also done the same using an entirely new startech adapter. Same problem.
Also tried repair install of Office thing it is an office problem since both word and excel behave the same, but then again, Google Chrome behaves the same also.