Exception when user works on CMS with same login in two windows of the same browser.

Scenario
User creates an link via xinha >> internal link where (s)he select new window options

Actual -
1. New window opens with dashboard screen
2. User is now allowed to work in both windows with same user-id.

Issue - At times throws exception (logs attached) while browsing thru docs or closing the tabs (using tabs mgmt options)