It's your DPI setting in Windows 7.
Right-click on your desktop and click Screen Resolution. Then click "Make text and other items larger or smaller". Set your DPI to 100%, logout, log back in, and you'll be good.
This might make things too tiny for comfortable viewing though, especially if you're on a laptop. Windows 7 will automatically crank the DPI up to make higher resolutions usable, and this is a side-effect of that.
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