Vista Ultimate Upgrade - error 0x8007001F at expanding files

I am not able to install the retail version of Windows Vista as an upgrade that I want to do from the RC installation. When I am trying to do the Upgrade Install then it warns me that some programs will not work after installation but it wont affect the installation of the OS. So, I start the setup and all the files are copied and when it reaches 100% then immediately after that it changes to expanding files 0% and then I get an error that says "Windows cannot install require files. Make sure all files required for installation are available, and restart the installation. Error code: 0x8007001f". Can anyone please help me out of this problem?

Even I am facing the same error if I am trying to install Windows Vista. But there is something I noticed that I am getting the error if I am installing Vista from within Windows XP, that is - I already booted to XP and then put the Vista DVD in the drive for the installation, then the problem starts. This problem was solved only after I did a boot install.

I wanted to know whether we can do a boot install as an upgrade over a previous instance because I want to keep all the settings and dont want to do a clean install since the RC2 till now has not expired for me.

Microsoft has released a cumulative update rollup for Windows Vista. This rollup helps establish a quality baseline for the USB core components on the Windows Vista operating system. This rollup supersedes previously-released USB fixes and contains additional high-applicability USB fixes. Just go to this link to get it - http://support.microsoft.com/default...b;en-us;936003

Also, you can have a look at a similar kind of thread which is discussed on the same issue over here - http://forums.techarena.in/operating...ms/1125636.htm