Installation reached the "Completing Installation" phase....

Installation reached the "Completing Installation" phase, the computer restarted and after getting past the new winows icon, a error box popped up that read "The computer restarted unexpectedly or and unknown error has occured and installation cannot be completed. Please click OK to restart the computer and restart installation." After I click it it just follows the same loop. My installation is from Vista ultimate to Home Premium. Per the instructions I did the custom installation and and had no problem until it got to the completing installation part. Any help with this would GREATLYappreciated.

Did you format the partition you were installing too? On a clean install it's best to delete previous partitions, if any, and re-configure new partitions and format them.

During the initial install phase, Windows 7 configures a hidden 100MB partition which is permanent. Did this occur? Give us more info is possible.

Thanks