FileMaker 7 is a very old version of FileMaker. It's possible that you will need to upgrade to a newer version in order to resolve this.
I would guess that this previously worked before. What changed? New computer? New printer? or ???
Before you go that route, here are some options to try:
Make a brand new simple test file if you have not already done so. Try printing from it to see if you get this issue. If you do not, there's something wrong with your original file.
Try printing to or saving as (if this Save AS PDF exists in FileMaker 7) a PDF and then try printing the PDF to your printer. A pain to do every time, but may allow you to avoid the upgrade (though you may soon run out of OS versions in new hardware that allow FileMaker 7 to work....)
Your Sharp printer tech support person probably already covered this one, but make sure that you have the latest printer driver downloaded and installed.
And sometimes, some printers in the Windows world can be substituted for the one specifically supplied for your printer. If Sharp tech support can identify an alternative driver to use, you might try that option. It's a major long shot, but costs you nothing to try.