I had this same issue and there was a pretty simple fix.
Exit Boxee and go to your Control Panel -> Appearance and Personalization -> Under "Display" click "Make text and other items larger or smaller"
Set your text to 100%.
Voila! (except you'll have to squint to read the text on your desktop)
For some reason, having your text set to be larger eats up a bigger amount of processing power than you might think.
If this doesn't work you might have other (bigger) issues.
Boxee 0.9.23.15885 on Windows 7 Home Premium (64bit), Acer Aspire X1301, AMD Athlon X2 215 (2.70GHz), 3G RAM, NVIDIA GeForce 9200