I have a canon i850 which is about 18 months old. Last night when my son was printing off a walkthrough from the web it started sparking and smoking so he turned it off. When I looked at it later I was unable to get it to print anything. The computer still recognised the printer and it went through the motions of printing but nothing is printed on the paper. After a while it started smoking from around the cartridge cradle again. I've got a feeling that the thing is dead, but wondered if anyone else had similar problems.
and, if it is "playing up" like that, I presume that you have already disconnected it and put it to one side somewhere safe ( fire hazzard if nowt else; erm..your smoke detectors ARE working in your house I presume..yes, I am serious!!)
Sadly we live in a disposable age, its unlikely it would be economical to repair it and you would probably be better buying a new printer. However before you do this I personally would try contacting Canon, I'm not saying it would help but I would say this is a pretty unusual fault and if you contacted them stressing the printer is only 18 months old and the danger of fire and how unhappy you are they MAY either offer you a new printer or perhaps a discount off a replacement. They're under no obligation of course as it past the year warranty but they may do this out of good customer relations. Anyway its worth a try and they may want to see it themselves anyway to find out what happened.