From the microsoft answers website.
Recovery options in Vista
Note this issue is caused due to the boot file corruption and in order to troubleshoot this issue we will run chkdsk from Win RE (Windows Recovery Environment )mode and check for the issue, to do that follow the below steps.
To run check disk, you have to have Windows 7 DVD, boot the computer to Win RE from the elevated command prompt, and try to do a CHKDSK. You can follow these steps to run CHKDSK :
1) Use the Windows 7 DVD to start the computer in Windows Recovery (WinRE).
2) In WinRE, open a command prompt. To do this, follow these steps:
On the Install Windows screen, select the appropriate Language to install, Time and
currency format, and Keyboard or input method options, and then click Next.
3) Click Repair your computer.
4) Click the 7 installation that you want to repair, and then click Next.
5) Click Command Prompt.
At the command prompt, type the following command, and then press ENTER:
chkdsk drive: /f and chkdsk drive: /r
(chkdsk F is to fix errors)(chkdsk r locates bad sectors and marks them)
If the issue persists, then I would recommend you perform startup repair. Follow these steps:
To perform a Startup Repair follow the steps below:
1. Please insert the Windows 7 DVD and reboot the computer.
2. When we are prompted to press a key to boot from the DVD, please press Enter or the space bar.
3. Choose your language settings, and then click Next.
4. Click Repair your computer.
5. Select the operating system you want to repair, and then click Next.
6. On the System Recovery Options menu, click Startup Repair. Startup Repair might prompt you to make choices as it tries to fix the problem, and if necessary, it might restart your computer as it makes repairs.
Access the link below for more information about startup repair:
Method 3: Memory Diagnostic Tool.
I would suggest you to run Memory Diagnostics from the Windows 7 DVD. To do this follow the steps given below:
1. Insert the Windows 7 DVD
2. Restart your computer
3. When asked if you want to boot from your DVD drive, do so.
4. Choose your language, click Next.
5. Click 'Repair your computer'
6. Select operating system you want repair.
7. On the System Recovery menu, click Memory Diagnostic Tool.
8. Your system will be restarted and your memory checked for errors
Refer the link given below:
Diagnosing memory problems on your computer: http://windows.micro...n-your-computer
this also works in Vista