Please try to delete your cookies and check if the problem still exists. When log- in to Sitefinity uncheck Remember Password option or try to login from another Browser.
To delete your browser's cookies:
1.IE>Tools menu>Internet Options
2. General Tab> Browsing History section > Click Delete button.
3. Select Cookies and click Delete
1. Firefox>Tools menu
2. Click Clear Recent History - select Cookies
3. Click Clear Now or use Ctrl+Shift+Delete
the Telerik team
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Public Issue Tracking
system and vote to affect the priority of the items