Wont take a picture displays error 99

Other than sending the camera to the shop to get replacement, you can do this method to temporarily solve the problem. Set the camera to P mode, go for Sensor Cleaning Mode, Manual Cleaning, and clean now... You will then hear the mirror lock and followed by ERR99! All you have to do now is to shut off the camera, take off the battery and waith few seconds. Reinstal the battery and immediately you'll hear the mirror resetting itself. The camera should be working just fine for now until you shut it off next. I suspect, this error are linked to the mirror or sensor lock up thingy....

My canon 350D with the kit lens recently started saying error 99. I tried to clean the contacts as suggested elsewhere but it didn't work. In my case it only happens with my kit lens(18-55mm). When I tried both my dad's kit lens and my own sigma lens there are no errors. Therefore the error seems to be with the lens and not the camera. I'm buying a new lens.