We have a problem on a Magento 1.9.0.1 store where if you use IE9 and log into your account then try to view a product this will somehow clear your session. It doesn't happen on any other page.
This problem seems similar to this question:
I have tried the solution of modifying the cookie timeout, set it to a week (86400 seconds) and changed the path and domain of the cookie through the Magento backend.
I have also tried disabling any modules that may be running on the product page and we still have the same issue.
Any pointers or ideas on what may be causing the problem would be useful.