I wonder if others have the same problem with the 2 week login. I've had to do this 3 times this week using the same computer despite marking the 2 week box. I'm pretty sure there were not 2 weeks between these prompts.
Yes various things, that shouldn't, cause it to logout anyway. I have it do it with visiting various Verizon pages, then trying to return to my verizon home page. Plus if you have your browser set to delete cookies, or have some internet protection software that does, you will also be logged out.
The VZ employees who post here will tell you that it is for your protection. Imagine a member of your household changing your settings or reading your email. Looks more like traffic control to me.