Check out http://www.weeno.com/art/0799/101.shtml.

Recall the bottom line thing the computer understands is a binary command. An "illegal instruction" means the computer has come across a command that it doesn't understand. (Not every combination of bits necessarily makes a legitimate op code - instruction - any more than every combination of letters makes a legitimate word.)

It's not clear that it's your server that's deciding you have performed an illegal operation.

I'd start by making sure that my system had the latest service pack on it. If I still had the problem, I'd install the latest browser. If still a problem, it would depend. I might switch browsers or upgrade to another OS.

k