Shoutbox

Messenger Plus! Live, being a user level program, is highly unlikely to bring down the system. However, Windows is not as immune to kernel crashes as systems like Linux, so if there's a number of problems concerning a number of apps, the combination can take down the system. In this case, it's likely to be another 3rd-party program that's also hooking into WLM, which conflicts with Plus! at a low level, causing system instability.

And the sort of program that will do that is spyware or a virus.