I've have been experiencing this "getting logged out" problem for weeks now but I just log myself back in - no big deal !!
For me, it happens if I minimise the Gameboomer screen whilst I look at something else on the web.
When I return to the Gameboomer screen I find I have been logged out.
It happens using both Chrome and IE11 - and I've tried all the suggestions that have been offered here to no avail.
[I don't use Firefox.]
Of course, if I ever couldn't log myself back in THAT would be a problem !!