Blank Post in Categories

Recently upgraded to 4.0 now when I click on a specific category all I get is a blank Page. Tried resetting my permalinks to default and de-activating my plugins with no luck. Any help would be appreciated.

FYI dont have much tech knowledge in this. So if you have an answer that requires changing something in one of the files, please be patient with me.

In need of desperate help on this as my site uses categories to post for online reservations and calendar upgrades.

Thanks