mobile theme
#2
It's simply cookie-based. So you're either not accepting cookies or the cookie is corrupt. The solution is to either accept cookies or delete the cookie if it's corrupt. Unfortunately if it's the latter, not all mobile browsers support singly deleting cookies and so you'd have to delete all cookies. Deleting all cookies means you'll lose automatic login for any sites you currently have and you'll have to revisit those sites and resupply your credentials.