Windows Vista installation fails on expanding files at 21%

I am a bit disappointed with Vista installation. I have a DVD with me that I had purchased from a nearby shop. When I started the setup, it failed on the installation screen. I thought this would be fixed if I do the setup again. But still the setup crashes on expanding files @ 21%. I am here trying to upgrade my old XP system to Vista. Before I had verified properly through Vista Upgrade Advisor that my system will support Vista or not. The setup is not at all going beyong 21%. Any idea on this.

There can be number of different things behind that. The CD might not be properly or there can be some kind of bad sectors in your drive. I will recommend you to perform a clean installation instead of upgrade. If stilt it is crashing go back to the shop and ask for replacement.

After a reboot, my upgrade seemed to be stuck at 21% for several minutes. About 35 min later as I was googling and reading through this thread, it started moving again.

The files inside the installation dvd are compressed. The cd unpack then and then the setup goes ahead. If any of those is corrupted or not proper this kind of issues are common. It is right that you must contact that shop for replacement. You can try to run the clean installation as mentioned above for one time.

Did you check the ram once. If you are having a multiple ram stick installed in your system then you can try installing Vista on single stick. There can be ram issue due to which you are getting the problem. I had faced the same thing on Windows XP. Everytime when I run the setup I got a skip file error. I changed the ram and things went back to fine.