Any chance your printer is substituting a font? (Does it work with one printer and not another?)
Did you redesign the entire file from scratch or just the layout? If just the layout...
If you recover the file are any problems reported? 5.5 doesn't tell you much, but it's still worth a try.
If you don't have an older back up copy to test, you might need to recover the file and carefully use the recovered copy for a while to see if it shows the same problem.