Page printing problems in 3.7.3 vs. 3.6.7

Printing "page" pages no longer functions properly after manually updating (with all fixes) from 3.6.7 to 3.7.3. Chrome still works okay, but both Firefox and IE produce blank first pages and then only some content on subsequent pages. Switching back to 3.6.7 (still installed in themes) corrects the problem.

Pages on our site (http://www.piercenet.com/previews/) are listed in the left sidebar as Product Articles. Individual pages have a right "sidebar" that is actually part of the center content in the page template, so it should (and normally does) print as part of the page.

Any thoughts on what underlying code change in 3.7.3 might have caused this function to break?