I don't judge K-lite codec pak, but codec packs in general + very noob users...
An expert (well.. even not too expert ;) ) user can use codec packs, even the worst one without having problems. I think too that K-lite CP is one of the better and well assembled codec paks, but even a so well made one (if used without consciousness) MAY lead to conflict problems
As I said I think that K-lite CP is one of the best CP out there