Long running script errors can usually be fixed by doing the following in Internet Explorer which I'm assuming you're using:

Go to Tools > Internet Options > Advanced. Under the Browsing heading ensure both of the "Disable script debugging" items are checked. There may be another box you can check to stop notification of long running script errors you can also check.

If you use a different browser there is probably similar procedure to do the same thing but I don't know specifics. I haven't seen this error in years.

That said, it's odd this is happening on multiple computers. Do you have anti-virus and anti-malware programs running and up to date?