Hi,
We are also having this same problem since last week. 2 of our employees can't login they just keep getting the script error.
I have tried all of MYOB's suggested fixed as per other posts i've seen on here (deleting browser history, deleting accountright cache, uninstalling and reinstalling program) and I just had our IT company try to fix this issue for the past 2 hours today and they have told me to go back to MYOB now as they have tried all they can without any success.
Wierdly, when I set a new login up on a different email address our employee was able to login fine so it just seems to be our particular current logins that are not working.
I hope there is some sort of resolution to this soon, from what I have been reading on the forum this has been going on for weeks.