Campagnolo Record C9 / Shimano CS-HG200-9 incompatibility I drive cheap Shimano cassettes together with Campagnolo Record C9 chains. Yesterday I installed a new C9 and a CS-HG200-9. But the chain sort of slips over the sprockets, not unlike really worn parts, but exactly once per revolution and under all loads. Has anyone else experience with this particular setup?

This Campagnolo chain is not incompatible with Shimano 9 speed cassettes in general: I've gone through a couple of these, and had overall good experience. I cannot remember when I changed to the last pair, but it's been more than one year - that means at least 11000 km, much of it commuting under all weather conditions with lots of acceleration and partially steep, fast ascension + some tours over some of the Swiss alps passes.
Might be a spec change by Shimano - I know that there is no change to the Campag chain. As they are not designed to be compatible, if Shimano have changed something they will have done so only referencing their own 9s HG type chain which is slightly narrower than Campagnolo's.

The other things to look at are a stiif link or a chain rivet protruding slightly at the join.

If it's once per crank rev (rather than once per full chain rev) it would be more likely to be related to the rings - if you are doing 11000km per chain / cassette I'd guess the rings might be getting pretty tired unless you are changing once every couple of chains - depends whose rings, riding conditions etc ...