I was getting the same thing. Even on government websites with no advertising.
The computer would lock up for 1/2 hour to an hour. WTF. Disconnect and do something else.
Firefox with only NoScript and Malwarebytes.
The typical errors were:
Script: resource:///components/nsPrompter.
js:466
Script: chrome://bprivacy/content/bprivacyutils.
js:20
Script: chrome://browser/content/sanitize.
js:133
Script: resource://gre/modules/XPCOMUtils.jsm:357
Downloaded Ghostery. So far nary a hick-up. Thx Brando
