Hey Paradisiac, just reposting from my own thread where I reported the same issue:
“By process of elimination, I went through all the programs that had been updated on my machine in the last 48 hours, disabled them one at a time, to see if that made a difference. And I managed to rectify the issue and get into the WP Dashboard on my laptop!
It looks like there was a conflict with the anti-virus software I was using. After uninstalling it, I was able to log in via WP Admin on any browser.
I need to see if reinstalling the anti-virus software will cause the conflict to reoccur, so perhaps I may need to chose a different AV solution going forward. But that seems to be the issue.
Thanks for all the help!”