Vista - Why give error codes if they don't help find the problem?

I just cannot get RC1 to get past the Expanding files portion of the
installation. I get the error code: 0x800706F8, which I have posted and
asked for suggestions on, and I can't get anyone to say that error code
equals this. Fix this, and the install will work. Isn't that what error
codes are for?

I have tried everything that I can think of and there has been no change in
the installation. Does anyone have any suggestions? Please let me know if
you do.

Also, if I can copy the DVD to the hard drive and load it from there, please
tell me how.

Thanks