When you need to fix a boot problem that has to do with the MBR (Master Boot Record) or the file system boot record then the Recovery Console can help. The two urls below are to Microsoft Knowledge Base articles that explain exactly how to fix boot problems.

http://support.microsoft.com/kb/307654

http://support.microsoft.com/default.aspx?scid=kb;EN-US;314058

To Access Other Directories While In Recovery Console

This security policy will also access to files and folders other than the defaults (normally access is restricted to \winnt and \cmdcons). To enable access to other folders, simply boot to the Recovery Console command prompt and type: 

set AllowAllPaths = true 

You will then be able to access other files and folders on your computer. Please keep in mind that this is a potential security problem, and that you should be careful to restrict physical access to computers that are configured in this way.