In my case it was checks in particular that weren't printing properly. I'm sure this could apply to other forms as well.

http://support.quickbooks.intuit.com/support/articles/HOW12177

If the printer prints correctly outside of QuickBooks:

1. Replace the QuickBooks Qbprint.qbp file:
2. Close QuickBooks.
3. Rename the qbprint.qbp file.
4. Open QuickBooks and attempt to print again.