Having Windows issue to Dell system and need to reload Windows operating system to factory setting condition.
Here is the step to restoring windows vista or windows 7 on Dell system.

1. Press F8 After the BIOS Screen (booting)
Choose Advanced Options for: Windows Vista







2. Select “Repair Your Computer” (Use the arrow keys to highlight your choice and press Enter)

3. Click the “Next” Button on language screen

4. Click the “OK” Button on Log on screen

5. Select “Dell DataSafe Restore and Emergency Backup”

6. Select “Select other System Backup and more option”

7. Select “Restore my Computer” 

8. Select “Factory Image” and click "Next"

9. Select “Restore without preserving new or changed files” (Red box)
10. Select “Yes, continue”
11. Click “Restart” button to complete the Restore

See also:
Repair Windows 7 Update Issues
Restoring Lost Data on Flash Disk
Intel Haswell platforms will not POST used with DDR3