In the main menu and the game menu I can move the mosue cursor around. but I cannot click on anything. In game I can zoom in to aim and shoot with LMB and RMB but I cannot move the camera around. I've tried to both update and roll back the driver for my mouse, but that didn't help.
I have the same problem, it worked perfectly for a bit, but now i can't click on anything in the menu, i can't move the camera, but in game i can shoot the Mako's weapons..
I had this problem as well, i found a "solution" here: http://answers.ea.com/t5/Mass-Effect-1/mass-effect-1-windows8-mouse-issue/m-p/3758163#U3758163