How to prevent deep-freezes?

System deep freezes happen when a mis-behaved process takes 100% CPU.

This is no big problem on a multi-core CPU (4 cores in my system), because you have an opportunity to notice a slow-down before any freeze occurs (as it would take 4 processes, each taking 100% of a core before a deep freeze occurs). However, such an occurrence is especially unacceptable on older, single core or even dual core systems.

Many KDE processes often misbehave this way: kde4, plasma-desktop, nepomuk processes, etc.

I consider this kind of bug to be critical and it shouldn't be allowed to happen. Shouldn't the distributions take dispositions to limit by default the amount of CPU that certain processes that are known to misbehave can take?

Also, an alarm can be set if any of those processes reach their limit: let the user know that a process might be stuck at its highest allowed level.