Mike keeps having problems where online forms won't accept his email address, saying it's not a valid email. It doesn't matter what browser or computer he uses. What gives? Leo says to make sure you're using a US region keyboard in the regional settings. It may have been changed unwittingly. It also could be an issue with your keyboard driver. Gmail also acknowledges dots and dashes in an email, while some websites do not. So if you have firstname.lastname@example.org, Gmail will accept that, but a form may not.
What Leo advises though, is to think about what is the common denominator on all those issues. It could be a security issue with your network. Check a different network: go down to a local Starbucks and log in to see if the problem occurs again. It could be that your ISP is blocking forms for some reason.