Problems with printing using Apple Express.

Hi from England, UK

I have 3 Macs, 2 MacBookPro's ( one early 2008, other bought recently) The MBP's are both running OS X 10.7.1, my ancient, but still very efficient G4 20" iMac running 10.4.11.

All three Macs connect to the internet with an Apple Express and ZyXEL ADSL Router/Modem (Prestige 600 series) provided by my ISP. I also use the Apple Express
to print wireless via it's USB port and to stream music to JBL speakers.

Both MBP's print fine via Apple Express, but a few days ago my G4 iMac refused to print wirelessly, but can still connect to the internet with it. Therefore, the Apple Express and G4 iMac aren't the problem, more like something I've cocked up on my iMac ?

I've deleted my current printer/scanner/copier Brother DPC 120C, and using Printer Utility have added it again, but still no luck printing from the iMac which I need to do at times.

Any ideas what I've done wrong ?

Jim
Mac User since 1994.