Chain slipping at rear.. chook,chook,chook!

Hey roadies hope you can help with a mechanical mystery:
I've had a Jamis Xenith since Sept 09 and used it to commute and train around Manchester for 2 years covering about 2000 miles.
A gear cable snapped in August which I had this replaced at a shop but they warned me of a worn drive train. Within 6 weeks the chain began to slip in higher gears when pushing off at lights. I saw this as an opportunity to get a new larger crank set to improve top speeds. The previous set was a compact set and had worn down the larger ring to 'waves' I purchased a near new crank FSA set with 53T from ebay. This did not solve the slipping.
I read a few forums and fitted a new chain, a new rear mech (which had worn and chipped jockey wheels)and hanger (which was bent in a crash on some ice.)
The only thing I have not upgraded recently is the rear cassette which does not appear to be excessively worn and has had wear spread across several gears anyway.

The slipping still occurs in any of the smallest 4 rings on the rear; 11-14T. I am currently unable to use the bike to train as any agressive acceleration causes the chain to slip/jump. It makes a noise like chook chook chook when trying to push in high gear.

Any ideas as I don't like getting passed.

Graeme