Blender crashes during weight-painting

I’ve been following along nicely with the “Intro. to Character Modelling” tut. Up to now everything’s gone well, until I got to the section on weight-painting the mesh. I managed to paint the first bone, but every time I go to paint the next Blender crashes.
Any help would be greatly appreciated. Each time it’s happened I’ve told Microsoft to “don’t send” error report, but should I “debug” and post something here?
I’m using WinXP, AMD64 3500+ w/1G of RAM, Blender 2.42, if that helps.
I guess I should try killing as many other apps as possible first, see if I’m just overloading things. But nothings slowing down, everything renders smooth and easy, so I doubt I’m crashing because of a lack of CPU power.
Thnx in advance for any suggestions.

first, try 2.42a. has lots o bug fixes. crashes are bad, and should be reported, but you have to have latest version.

Take a look at this post and verify that you have a valid Armature modifier, with an existing armature name filled in.