Using Fullscreen (wide) mode, all settings at default.
I am using an iMac OS10.8.3, 2.66GHz Intel Core 2 Duo, 4 GB 1067 MHz DDR3, with an NVIDIA GeForce 9400 256 MB graphics card.
I also have a Microsoft Wireless Laser Mouse 5000, but have used a wireless Logitech M310 and the problem remains the same.
Any thoughts? MIght there be a thread about this issue that I'm missing?