I would first like to say hello to all my fellow forum users I am happy to be aboard.

My problem...
I am having a problem with my chain slipping off while riding my road bike. It happens when i am on the big ring and pushing a big gear up hill. My chain doesn't seem to be able to handle the stress put on it and simply slips off...i am wondering has it streched It is a major problem at the minute because a few times this week it has almost sent me crashing to the tarmac.
I would appreciate any comments as to the cause of this problem and any actions needed to be taken to correct it.

Thanks in advance for any help and comments offered!!