Chains and Slipping....

I was wondering if a cheap chain can lead to it slipping, I have recently changed my block and chain for new version and all was good for a short while, however the other night it started slipping, just in the small cog @ the back and it makes a horrible noise.....It only feels like it slips one tooth but my immediate reaction is to ease up so I don't know if it would slip further if I kept applying pressure....
The chain is a generic and the block is even more generic, I'm in the process of trying to find a new Campag derailer so will get a nice period block for when I have this but I just need to be able to ride it at the moment...
Do chains stretch? If so would this be a symptom? The bike does have drop out adjusters but I'm not sure if these would help?
Any advice would be much appreciated!
Happy Riding
Tom

If you have just changed the chain, I suspect that you have a tight link. It does feel ghastly when the tight link jumps on the cog.

Agreed could be a tight link, wind the pedals backward and watch how the chain runs over the block and down to the jockey wheels on the rear mech.
If there's a tight link or even a part missing then it will become apparent.

Have you checked the chain length? Could be too long.

I recently had this sort of slippage, but that was a new chain on an old cassette. Was the cassette / block new?

Both the chain and block were about 2 months old...turns out I managed to split the two smallest gears...
Block replaced so should be up and running
Wonder how long this one will last...
Thanks for the ideas though!!