Download link broken in firefox for ebook purchases

Hey there!

Got an email from a customer this morning that she downloaded the pdf she bought from and then couldn't open it. Through some emails back and forth, I found that there were no problems when downloading the pdf via chrome, but when you download via firefox it downloads a corrupted file.

You can test this for yourself by putting this product in the shopping cart:

and then using coupon code BOOKTEST so you don't have to go through paypal for anything.

Again - download link in email works in chrome, but produces a broken file in firefox. HALP!

Thanks guys.