Well... since TS had already make a mistake and many had already hammered him/her/it enough. But this is a newbie section, whereby other newbies do read it occasionally so for the benefits of the other newbies I will give a bit of help here (according to reading of other threads).
1) When and Err 1 occured, do try to switch off your camera, take out your battery, reinsert your battery, switch on the camera again and take a shot.
2) If the problem persist, dismount the lens, clean both the lens contact and your camera mount contacts, the re-mount the lens and take a shot. If it still persist,
3) remove lens, mount new lens and take a shot... If there are no Err1 error, then most likely the problem lies with your previous lens. If you see the same problem, then most probably there is some problem with your camera body.
4) If 3) happen, you can either DIY the repair yourself, sent it down to CSC or look for a repair shop like Camera Hospital, or look for our friendly and very good bro in CS - Fatigue.
Problem,
If it is your lens problem, well... there is this flex cable in your lens that might be broken;
a)
Flickr: Discussing Error 01 in Canon EF 24-105mm f/4 L IS USM
b)
Err 01: EF-S 17-55mm f/2.8 IS only at long focal lengths - Canon Digital Photography Forums
c)
Re: 17-55mm 2.8 err01 message: Canon SLR Lens Talk Forum: Digital Photography Review
d)
Repair of an Canon EF 17-85 IS lens (Januari 2009)
Actually this seemed a common issue with some of Canon lenses like:
1) 24-105mm F4L IS
2) 17-85mm
3) 17-55mm f2.8
4) 18-55mm (although mine still work after all these times)