Hi Susan and welcome!
I've moved your question to our support forum.
That is actually a setting on your browser that is doing that. Find the settings that allow cookies, and set it to allow cookies from
Splitcoaststampers: Stamping, Stamps, Card Making Ideas, Paper Crafts & Template Gallery
Your login information is contained in a cookie, and your browser is rejecting that.
Hope that helps! Welcome, and please let me know if I can help you with anything else!