Yes, it is the browser. Unfortunately IE 9, 10 and 11 don't mesh well with the software we are using. As this past year has gone along, I am finding more and more sites out there which don't do well with the IE11 which I am using. With the popularity of MS browsers in the dumper today, less than 10% of us using it any more.....
I really hate IE , and have never used Safari . For me Google Chrome works well and I've never seen any of these sign in problems . Does IE allow you to dump your cookies when you sign out ?
I found another IE clue -- most every time I'm requested to repeatedly sign on during a site visit, the two little pop-up site notifications (Telethon and Site Changes) appear in the lower right. I'll turn on the pop-up blocker and see if that has any effect.
Thanks -- just found that out. It's interesting though that they appear only when I have to repeatedly sign in.