Browser crashes?

I have a really strange error with one of the flashfiles I’m working on.

The whole thing looks like a spiderweb and to the right I have a lot of checkboxes. When I click on a checkbox a line expands over the “spiderweb”. And there is 5 of these “grouped lines”.

the code is spread all over the place so it’s hard to give a real example. The problem is that when some people runs the flashfile they get an error and their browser goes down and they get an standard windows error message.

This only happends on some computers, anyone got an idéa of what the problem might be???