Was he trying to use Latex over an oil based/enamel paint? Won't work unless it's prepped first by either sanding, or being primed first by paint that can transition oil based paint to accepting latex, which will always peel, though the opposite is not true.

Have the walls ever been whitewashed or painted with calcimine paint? Both of those will cause peeling, but I don't know what the solution is. I'd hesitate to paper until the peeling mystery is resolved - that may make an even bigger mess!

Pics of the peeling paint could help narrow down the culprit.

I would suspect that lucy's thought was correct but if it is calcimine( which was normaly done on ceilings) here is an article on that.Either way do not hang paper on top of the problem,as you will just be creating a bigger one.

Here is a link that might be useful: calcimine