Canon 40D won't take photos

Has anyone had the problem of pressing the shutter half way and it will focus and then when actually pressing it all the way to take the photo it just doesn't do anything? I've tried it outside and with a flash just incase it was too dark.
I've never had this problem before and I've also noticed that the +2 has gone from next to AEB on the menu. Any help would be useful. I'm taking it back to the shop but what would I expect as I need this camera 2 weeks time. How long do Canon in the Uk take to repair or could I insist on a replacement. I bought it in February 09.

I've had some weird problems with my 5d2, have you tried removing the battery and putting back in, or re-charging, or different battery? also try re-seating the lens, or if you have another lens trying it? maybe even cleaning the contacts on the lens and body?

Shutter button is a common failure on 40D's. Mine was replaced under warranty.

My 20D does that when the shutter button is active to Auto focus. Try turning off the AF or switching it to the back focus button ( much better) and see if it still fails.

I've tried different lenses and cleaning the contacts but surely that would affect the focus not actual not taking a photo?
But surprise, suprise it worked in the shop but the AEB on the menu has gone funny and the middle bar is bellow 0 and the +2 has gone but when the manager had a fiddle it went back to normal. He'd never seen that so is going to phone canon for advice.

If the AEB scale read '-4 3 2 1 0' that meant that the EC was (probably inadvertently) set to -2.
If it read '-3 2 1 0 1" the EC was set to -1.

When in One Shot focus mode the camera will not take a shot until the lens has reported "focus acheived".

That could explain it. But it didn't go past -2 which I would expect if if the +2 went off the scale.

If it's only half a step it's enough to loose one end, but not enough to get a new digit in the other end.