illegal operations

[PotsNPans]

I seem to be getting a lot of error messages lately that say "illegal operation." How is an "illegal operation" different from other kinds of computer errors? What's the biggest cause of illegal operations and how can you avoid it?

[suwunk]

An illegal operation, a term often seen in error messages, is a command to the operating system or an instruction to the computer processor that specifies an operation that is unknown to the operating system or processor and that therefore can't be performed. The result is that the operating system or processor usually terminates the program that made the "illegal" request. If that program was an application that you were using, you may find that data you were entering was lost or, in some cases, can be recovered from a backed-up copy that the system made for you.

How to fix it:
How do I fix illegal operations