My Zebra 105SL printer prints a black bar over the entire label..why is that?

SOURCE: ZEBRA 105SL : PRINTING PROBLEM

Thanks your the solution. This helped me a lot.

Greetings
Thomas

SOURCE: Zebra 105sl - printer does not print correct size

This can happen if you have the wrong dpi setup. For instance the 105sl can be either 203dpi or 300dpi. If your printhead is 300dpi and the label you create is expecting 203dpi, then you will see shrunken label. Your situation doesn't exactly sound like this is the case but it may be worth checking.

SOURCE: Zebra 105 SE Printing Blank Labels

Seagull Scientific has drivers. Their Zebra driver is recommended by many.
http://www.seagullscientific.com/aspx/drvrmain.aspx

That's the link for their printer drivers page. Go to the bottom and click on 'Download a printer driver'. Then scroll the list to find the one you need.

SOURCE: Zebra LP2844 printer prints garbage

Sounds like you might be using a bad driver, or the printer is in dump mode.
Try hitting the green button and see if it says exiting dump.
If still having trouble, inside the printer it tells you that if you are having printing trouble:

1. turn off the printer
   
2. Hold down the feed button
   
3. turn on the printer and at the third red flash release the feed button
   
4. it will then feed some pagessome info and ask you to hit feed again to exit dump
   
5. hit feed again and it will say exiting dump
   

SOURCE: An extra, blank label prints from a Zebra 2746e.

Check media settings in the printer driver. Check version of printer driver. Zebra printersuse an internal printer driver with their Zebra Designer software (Zdesigner driver) or a ZUD (Zebra Universal Driver) for other windows applications. These drivers can be downloaded directly from the zebra website.

Alternatively you can download the seagull scientific driver and use that instead. (used with bartender program)

Label skipping occurs if the media dimensions are not specified correctly. The important ones are label height, and media setting for type of media.

Perform a media calibration before you go changing settings. Power on printer, Hold top and bottom buttons in on control panel for 5 seconds, release bottom button only then when printer starts feeding labels release top button. When printer finishes press feed button.