How do you restore MediaDirect 4.0.5506?

In a vain attempt to upgrade my version of MediaDirect, so as to play the new blu-ray extended version of AVATAR, MediaDirect became corrupted and refused to launch. After uninstalling MediaDirect 4.0.5506, I installed the MediaDirect disc that came with my system and then installed about 6 upgrades that it recommend before realizing that I was in an upgrade loop. I had re-installed the exact same upgrade 5 times over.

The current version of MediaDirect I have is 4.0.4707, but my current selection of blu-ray discs require version 4.0.5506. Does anyone know where I can find an upgrade for the latest version?

I have a Studio 1735 laptop with vista x86 and ATI 3650 video.  

Addendum:

It seems this is a common enough problem. MediaDirect 4.0 (AKA 4.7) is unreliable with its automatic upgrading system. It will either fail to update when there is an update, repeatedly offer the last update already installed, or update properly. I do not know what the current version of MediaDirect 4.0 is. Version 4.0.5506 might not be the latest version!

Dell tech support advised me to uninstall MediaDirect 4.0 and try reinstalling it until the updates all install themselves properly. But that seems like a crap shoot. I could end up worse off than I am now.

There must be a way to manually download all the updates in order, or to manually download one large cumulative update to the latest version of MediaDirect 4.0.  The automatic update system is just too unreliable for anyone having to restore MediaDirect 4.0 from scratch.