Offie 365 log in window suddenly disappears.

I have an Office 365 subscription, and when I try to open a file (Word or Excel), a window tells me to connect to my account. I type my email, and another window opens, but for only a second, not leaving me enough time to type in my password. I've deleted and reinstalled the app without success. The MS support was not able to help and advised I post here for help.

Thank you!