I have a Dell Inspiron with Windows Vista. On starting up, it says, "Windows failed to start. A recent hardware or software change might be the cause." then offers to "Launch Startup Repair" or "Start Windows normally".

When asked to start normally, it tries to start, but fails, returning again to this page.
When asked to launch startup repair, it opens the programme, scans the system for several minutes, and then says "Startup Repair cannot repair this computer automatically".

When clicking on the diagnostic and repair details, it says:

"Last successful boot time: 10/3/2011 3:42:52PM
Number of repair attempts: 8

Session details
System disk = \Device\Harddisk
Windows directory = C:\Windows
AutoChk Run = 0
Number of root causes = 1

Test Performed:
Name: Check for updates
Result: Completed successfully. Error code = 0x0
Name: System disk test
Result: Completed successfully. Error code = 0x0
Name: Disk failure diagnosis
Result: Completed successfully. Error code = 0x0
Name: Disk metadata test
Result: Completed successfully. Error code = 0x0
Name: Target OS test
Result: Completed successfully. Error code = 0x0
Name: Volume content check
Result: Completed successfully. Error code = 0x0
Name: Boot manager diagnosis
Result: Completed successfully. Error code = 0x0
Name: System boot log diagnosis
Result: Completed successfully. Error code = 0x0
Name: Event log diagnosis
Result: Completed successfully. Error code = 0x0
Name: Internal state check
Result: Completed successfully. Error code = 0x0

Root cause found:
Startup Repair has tried several times but still cannot determine the cause of the problem."

Otherwise one can view the advanced settings:
System Restore = "No restore points have been created on your computer's system disk. To create a restore point open System Protection"
Windows Complete PC Restore = "a valid backup location could not be found. Windows cannot find a backup on this computer."
Windows Memory Diagnostic Tool = didn't solve anything when scanned
Command Prompt
Dell Factory Image Restore = haven't tried but am avoiding wiping the whole harddisk clean for as long as possible..

It will not go into Sfe Mode, and I don't know what's going on. It happened when I shut it down (by holding down the power button) mid update as it had frozen.
What should I do? Thanks.

What is the make of your harddrive?

Um.. Sorry, not a computer pro, I'm afraid.. Where would I find that? Thanks!

Download the free version of System Information for Windows (SIW.exe). When you install it and click it on it will give you a two-panel window. On the left and much smaller window is a list of various items you can click on and the information will appear in the larger right hand window.

Scroll down until you find hardware and then look for the Storage Devices. Click that on and in the right window it will give you make/manufacture of your hard drive.