Sigma 120-400mm F/4.5-5.6 Knightmare

Please help, I have brought the Sigma 120-400mm lens new from someone on EBay. The lens is a canon fit, which is mounted on the canon 400D.
The problem I have is an extraordinary one, it will work indoors, but not outdoors! I can shoot from indoors, to a subject outside. As soon as I take the camera into the light, the back of the camera records an error message, telling me to turn the camera on and off. When I change the lens, I get no such message. Any help on this matter would be gratefully received.

Many thanks

Which error message exactly?

That is a real odd lens. Vampire perhaps? As foxbat said, what is the error message?

Also, what modes does this occur in?

I'm trying this lens out and out of curiosity I just tried it with my 400D like you did, but it just works, no error messages. Not heard of this type of error.

May be there is some record breaking heat wave going on in England that is making this lens heat up quickly outdoors.

The only time I've ever seen something similar is when I accidentally left the camera on iso 1600 in the day time and the camera was warning me the shutter speed had maxed out at 1/4000 and I was still going to overexpose.

Can you list details of the exact error message you're getting, and what mode your camera is in, etc.