I've created two customer login accounts. I log in with customer 1 then customer2. When i'm clicking around in customers 1 account customers 2 data is displayed.
I have <session_save><![CDATA[files]]></session_save> in my app/etc/local.xml
I'm using Chrome to test and i'm Right Click->Inspect->Application->Cookies and i'm seeing the adminhtml value change when the bug occurs.
Why are my sessions messed up and loading other customers information?
This is usually not a session problem. Mostly it is caused by misconfiguration of Full Page cache.
Try to disable and clear all caches Purge all files in /var/session and try again