This is a weird issue. The vertical lines of tabulars and frameboxes get broken at the top, but only when printed (the PDF is fine). I've been using the same LaTeX code for more than a decade and never had a problem with any printer, until now. The PDF is 1.4. I converted it to PDF/A, which is 1.3, hoping it could fix it, but it's still printed wrong. The printer is a Ricoh IM C4500, and I don't know if I had previously printed documents with tabulars or frameboxes in this printer. But with other printers it was always fine for sure.
As you can see in the attached images, the PDF is fine, but the printed output is wrong. This is an example with a tabular, but with frameboxes you get exactly the same problem. Have you ever seen this before? What could be the reason?

pdf2ps yourfile.pdfand then open and (physically) print the resulting.psfile? If that works well then there is some issue on how the Ricoh printer/printer driver interprets the pdf, which might be solved by either upgrading or downgrading the printer drivers.:-)