The best way to see what's going on is to actually go to the DAZ thread in the Carrara forum.  You don't have to have an account with DAZ either (at least I don't think so) to read.

Go to the DAZ site.

www.daz3d.com

Click on the "Community" link at the top.

Hold your mouse over the "Forum" link and let it expand to see the topics.  Then click on Carrara.

Then select the Carrara 8.1 beta build is out thread thingamathingama.

There's a list of all the bug fixes and stuff.

In terms of getting C8 to run on your system, I don't think they've upgraded C8 in ways that would fix that (not sure though as I'm not a C developer).  Your issue sounds different than the bug fixes they're working on (guessing though).

Since I have no idea what your situation is (how you installed, system, etc., and since I'm not a C developer), I don't know how to help.  I can only think of two ideas and there are lots of other people here in the forum who can help.

First, start a new thread here describing your problem.
Second, contact DAZ and see what they have to say.

My gut reaction is to COMPLETELY remove C8 from your system and try again with the latest version.

-Kix