I haven't been able to use the Find All Posts function for a while.
If I want to find posts I have made, I go to "User CP" towards the top of the page, open it, and then select "List Subscriptions" from the column to the left. When the subscriptions opens, if there are a lot, you can go to "View All Subscribed Threads" located over the list, click on it, and all threads where you have posted will show up.
When you open up the thread you will still have to find your post.
This might take a few more steps, but its a sure way to find something you posted.