This is the issue with the beta versions. There were warnings that using such can result in a wipe and start over of this OS.
Remember that admonishment?
Now about your post. I didn't read an error message for us to latch onto because... you didn't write it.
I can't install any new revisions of the service pack 2 updates on top of my existing SP2 full copy. Any attempts to do it (web installer as well as full downloads) result in vague error messages that just say it can't be done. One of the messages says to uninstall the previous build. How do you "uninstall a build?" That's lame.
I'm beginning to get errors now that keep reminding me that important security and performance updates can be obtained by upgrading my configuration but whenever I try it won't let me, without any good explanation as to the cause of the error or what to do about it.