It seems to happen when a session expires for one of the accounts. I keep my browser open for long periods and almost never reboot, and also have two accounts open, a gmail account and a school account. Generally there is no problem, but...
Scenario 1) I have both open, and log out of my gmail account. It redirects to my school's "goodbye" page. I just reproduced this. Not a huge problem, but indicative of a bigger issue.
Scenario 2) Now log out of the school account. I am greeted with a login for my gmail account. This is pretty close to the problem in Scenario 3, below.
Scenario 3) The real issue. The problem is not so much that it has happened, it's that there is no way to recover if you don't have the password. The other week I logged into my wife's laptop to grab a document from gmail to print, since it was hooked up to the printer. She didn't use it for the next few days. When she went to her work email's address (a .gov domain), it prompted her for my gmail password. There was no way to 'change account' at that point. No way to log out. Go to the .gov domain, get a prompt to login as <me>@gmail.com. No way to authenticate. I couldn't figure it out, and finally just logged in as myself then logged out, after which I was redirected to the .gov boodbye page, but it allowed her to log in after that.
Edit: Scenario 4) Go to www.gmail.com/a/umbc.edu, which the google help pages say is the correct way to go to the school's site. I just tried this, and it sent me to my gmail.com inbox. It is pretty much a crap shoot which mailbox I get when I first load the page. Sometimes it's aware I'm signed in under different IDs, sometimes not, so I can't always change accounts, and must go through login/logout hell to get them clear. Perhaps I could just clear my cookies but I don't like doing this en masse.
Yeah, there's something weird about the URLs to do with users. I've found myself regularly removing the /u/1/ part of G+ permalinks, for instance, which indicates that the user is being tracked oddly.
Scenario 1) I have both open, and log out of my gmail account. It redirects to my school's "goodbye" page. I just reproduced this. Not a huge problem, but indicative of a bigger issue.
Scenario 2) Now log out of the school account. I am greeted with a login for my gmail account. This is pretty close to the problem in Scenario 3, below.
Scenario 3) The real issue. The problem is not so much that it has happened, it's that there is no way to recover if you don't have the password. The other week I logged into my wife's laptop to grab a document from gmail to print, since it was hooked up to the printer. She didn't use it for the next few days. When she went to her work email's address (a .gov domain), it prompted her for my gmail password. There was no way to 'change account' at that point. No way to log out. Go to the .gov domain, get a prompt to login as <me>@gmail.com. No way to authenticate. I couldn't figure it out, and finally just logged in as myself then logged out, after which I was redirected to the .gov boodbye page, but it allowed her to log in after that.
Edit: Scenario 4) Go to www.gmail.com/a/umbc.edu, which the google help pages say is the correct way to go to the school's site. I just tried this, and it sent me to my gmail.com inbox. It is pretty much a crap shoot which mailbox I get when I first load the page. Sometimes it's aware I'm signed in under different IDs, sometimes not, so I can't always change accounts, and must go through login/logout hell to get them clear. Perhaps I could just clear my cookies but I don't like doing this en masse.