Outlook keeps prompting for password

Question

This is a weird situation.  User logs in to domain without issues and is able to access outlook.  However, during the middle of the day,  outlook keeps prompting user for authentication or password.
Profile has been re-created.  ESSO cache was cleared, but still the same thing. Created separate email profile for other email accounts she access, but same issue still occurs.
Has anyone seen this issue and what resolution have you used.

Answer 1

Truly I don't mean to disparage your comment/proposed answer, but in today's day and age one should really never, ever use "Remember my Password" for any context.  This means web forms even on trusted sites and/or when the windows subsystem
is called to prompt you for your Windows Password.
This is a very bad practice for two reasons:
The first is due to Heartbleed and/or the like-wise thousands of malware that are constantly attempting to hijack your username/password entry.  Please understand that when you ask systems to remember your password what is happening on the backend. 
That password is being saved somewhere, or a cookie is being set.  The only "safe" way to remember your password is in your head. 
The second is due to account lockouts. If you routinely use "Remember my Password", especially across several computers (home, work) and devices (ActiveSync on iPhone/iPad, etc.) then you are a prime candidate for getting a locked out domain account.
We, in IT, won't like you very much after that :)  Please understand that when you choose that option, those features do not remember to update all those places you have saved when you reset your password (every 90, 120 days, whatever your organization's
password policy dictates).  As soon as you do, you will begin to lock out all sorts of applications and/or your domain account.
As I said above, the only "safe" place for you to store your password is in your brain.  Now this gets difficult over time because you also don't want to use the same password over and over again for different places.  Because when you
do get compromised (and I do mean when, not "if") that hacker will not only have your password, but also will know where all you have used it.  And the first place they will go is your online Bank, Savings, online stock, etc...  If
you don't routinely rotate your passwords, and use different ones then you may just as well hand over the keys to your house.
Use a format like "for every letter O, I will use a zero", "I will use a 3 for the letter E" or "instead of the letter S, I will use a 5", then pick something only you would remember, like "that trip to Puerto Rico
was memorable"... so your new password would be Pu3rt0 5ic0.  Throwing in a space helps combat robot hacking.  Now this is slightly bad too though because they are dictionary or common words.  Then keep on that theme and think up a few
more passwords that you will remember, AirPlan3 Tix, 5andy B3ach3s! <-- and if/when they require special chars, throw a "bang" or "exclamation mark" on there.
If this seems a huge imposition (my gut would tell you to get over it, but in IT, hey we try to help too!) ask your Systems Admins/Architects to implement a Federation provider (like OKTA or OneLogin, or ADFS - probably least preferable).  Then they
can setup the multitude of hosted service providers (think "cloud applications" though I hate that word) for either SAML based Single Sign On, or leverage that service's proprietary "Password Safe" aka "Secure Web Authentication". 
Or lastly, for yourself you can go download KeePass.  This is a "wallet" style application that you can lock away all your passwords; though you will need to remember to update them in KeePass as you then may reset them.  Single Sign On
is always more preferential because they will typically use your Domain credentials (i.e., Kerberos authentication local to your Org's domain) as part of the solution.