nope, the system is a squeaky clean, fresh install, never been used for anything else.
I've looked for brains, tool offsets and have pulled out hair trying to track this down. Hadn't thought of plugins though, but definitley haven't run any on purpose. I'll check on that. Strange that two machines would have the same issue though....
Interestingly - if I run the button script from the code window (edit button script) and single step through, it works exactly as expected.
I'm just fortunate that this doesn't break anything. and is therefore a bit on an intellectual curiosity. There are other points in the cycle where an unexpected X / Y move would be costly.
Tim