Error99

OK I know it's Canon's all encompassing some thing's gone wrong but we're not sure what error, I've had it a few times before but usually 5 minutes with the batteries out cures it. I was taking a few macro shots tonight with a Sigma 50mm on, when I finished I switched off removed the CF card and reviewed the pics on the computer. Still with the 20D turned off and no CF card in I changed the lens to my EFS 17-85 USM IS, as soon as the lens clicked in to position the shutter started firing continuously. I removed the lens straight away but the camera kept firing for about another 3 or 4 times and up popped the error99. Took the battery out for 5 minutes and tried again but the camera refused to turn on, persevered for a while but no joy. If the lens is on it won't turn on at all and if you remove the lens it will turn on but within a nano second it goes straight to Error99, any body come across this before or is it back to shop it goes as it's still under warranty.

Take the camera and lenses back to the shop, they sound faulty to me.

Well it's back at the shop and they're going to send it off to Canon as it's still under warranty, they say it will be about 4 weeks AAAAAAAAAGGGHHH!!!!!!

I'm sure it's frustrating spending 4 weeks without such a great camera but I would take the opportunity to push your Powershot to it's limits and see what you can do with it, if you haven't already. If you have, use what you know of it to get the best shots you can. At least you're not completely without a camera.