Check this out:
[url]http://support.microsoft.com/kb/932932/[/url]

"gavtheunchav" <gavtheunchav@discussions.microsoft.com> wrote in message
news:DEED68D3-ADB4-4099-AE3C-7920854DAE7A@microsoft.com...[color=blue]
> since this morning, as i boot my laptop (Vista) it says that the operating
> system cannot be found... any ideas on how to fix this? Thanks[/color]