LOGIN problems - on the Lenovo laptop

Hi. It is not possible for me to login to login.arduino.cc on my laptop computer. It works fine on my desktop. I created IoT stuff on the laptop some two months ago. No problem.
When I try to login now to create for example new Things and Dashboards, I get a blank screen. It seems as if it has accepted the loginname and pwd. If I change my password, it prompts me for that and then same stop.
Cleared the cache. Deleted all cookies. Tried Firefox, Microsoft Edge, Chrome. Same problem.
The URL reads something like this: https://login.arduino.cc/mf?state=hK.(a long list of letters and numbers).
I also tried a different internetconnection. It MUST be the account because when I created a new arduino-user and logged in with that - it worked perfectly on the Lenovo.

Tried a different browser yet? Clear all browser data, particularly cookies?

Yes, cleared all cookies. Same result.

That's odd!
You could try booting from a Linux USB stick and see ifthe problem persists. I bet it doens't, but it doesn't help all that much in nailing it down any further.

Yes, funny thing is, that I can log in on my iPad and desktop without any problems. And with a new account on the Lenovo. So it must have something to do with that useraccount.

Really odd! sorry, I've not had this happen!