Hi,
Thanks for posting in Microsoft TechNet Forum.
Regarding this kind of issue, you need to perform a reinstallation. For more information, please refer to the following website.
When you start a Windows Vista-based computer, the system may stop responding (hang) at a black screen
http://support.microsoft.com/kb/946532
By the way, if you don't own a Windows Vista Recovery disc, you can download the ISO file at the supplied link, and make a Bootable Disk from it. For detail information, please visit the following website:
http://neosmart.net/blog/2008/windows-vista-recovery-disc-download/
Note: We provide this link for references, Microsoft doesn't control and guarantee the security and index information. There may be some changes without notice.
Hope this helps. Thanks.