I didn't need another reason to hate Internet Explorer but I found one. It turns out that if you use certain fonts at certain sizes in IE then the decenders get cut off. Ok, lets break that down.
A decender is the part of a letter (typically a lowercase letter) that drops down below the baseline. Here are the usual suspects: g,j,p,q,y. On occasion you may come across a font that include some other decenders but they are rare, and they are certainly not web safe fonts.