such messages usually popup if thers an error in the machine itself...also i this its a strategy from hp as it does not allow users to use toners/cartridges other than their own brand...just saying!!!!

thanku for this useful information on how to replace toner cartridges for Brother HL-5240...its clear with the images used....most helpful indeed!!!

can also log on to http://www.tonertree.com for some exciting products!!!!