Windows failed to start?

So I tried to install a game demo, which finished then asked me if i wanted to restart the computer, so I did. When it starts up it says:

Windos failed to start. A recent hardware or software change may be the cause. To fix the problem:

1. Insert your Windows Installation disc and restart the computer
2. choose your language settings, then click Next
3. Click "repair your computer"

File: \Windows\System32\drivers\sfsync.02.sys

Status: 0xc0000428

Info: Windows cannot verify the difital signature for this file.

If I put in my Vista disc then it comes up with another screen asking If I want to run in Safe mode, run normally etc.

My keyboard won’t work on this screen so I can’t select anything!! What do I do? I really don’t want to have all my stuff wiped so please help…
I would try to do that but my keyboard won’t respond when the screen comes up, so I can’t select anything.

my aunt asked me to install Windows Vista Home Premium on her comp.,she had XP and it saysWindows Vista capable.When Installing I selected the Upgrade option instead of doing the clean installation. no problems installing,but afterwards everything is running slow. Ibrought the comp.to my house to use dsl &installed all the the windows updates in hopes that it would solve the slowness. When that was done the computer restarted itself &said it was configuring the updates & then when I came back to check on it Windows Boot Manager was on the screen saying:
"Windows failed to start. A recent hardware or software change might be the cause. To fix the problem:
1.Insert you Windows installation disc and restart your computer.
2. Choose your language settings, and then click NEXT
3. Click REPAIR YOUR COMPUTER
…File: \windows\system32\winload.exe status: 0xc000000f

When i put the vista or the hp reinstall disc in nothing happens. PLEASE help I really dont want to lose everthing. THANKS.
I can’t get past the Windows Boot Manager, I tried pressing F8 to try and get it back to last known good configuration, but pressing F8 doesn’t do anything. I’d be happy if I could just get back to the XP version so she doesn’t lose any of her programs, and then trying to re-install Vista while connected to the internet.

Brand new Asus model X83V. Had it for about 2 weeks. I turned it off (properly) and left it alone for about 2 hours. When I turned it back on "Windows boot Manager" came up with the following message;

"Windows failed to start. A recent hardware or software change might be the cause. To fix the problem:
1. Insert your Windows installation disc and restart your computer.
2. Choose your language settings, and then click Next.
3. Click "Repair your computer."

File: \Windows\system32\kdcom.dll
Status: 0xc0000098
Info: Windows failed to load because the kernal debugger DLL is missing, or corrupt"

I have not installed anything since 2 weeks ago. I do not have a Windows disc. I have a recovery disc, but if I run that I will lose my pictures. My pictures are super important to me. I would lose all the pictures from my daughters birthday, among other important pictures I just can’t lose! Please help!

i have an acer aspire M5640 and when i press the start button a few seconds later i it fails to boot up with the following symptoms:

I get a message saying "Windows failed to start. A recent hardware or software change might be the cause. i says something about a installation disc and i dont have it. it also gives me the following options 1. Insert your Windows installation disc and restart the computer.
2. Choose your language settings and click next.
3. Click "repair your computer"

It also gives me the following options:

4. Safe Mode
5. Safe Mode with networking
6. Safe Mode with Command Prompt
7. Last known good configuration
8. Start Windows normally
none see to work. what can i do only a true geniusis can answer this so please help:)