If you try to print the same document from the same computer multiple times (reset the printer after each time you get garbage), do you always get garbage, or does the document print OK some of the time? If it prints OK some of the time, then interference (or a bad wireless interface) is the most likely culprit. If you always get garbage with a particular document and computer, try printing from the computer, but use a copy of the printer driver that is set to use a wired connection. If it prints OK every time then, you have a wireless problem (or a wireless driver setup problem). If you still get garbage with a wired connection, then it is either a document problem, or possibly an issue with either the basic driver code or not enough printer memory. If this is the case, post the document type and size (of the file on disk), and the driver version, and how much memory the printer has. An updated driver might be available, or, if possible a printer memory upgrade might be needed. Try printing the document page by page to see if you can get any pages, or determine which page the printer does not like.