Hey, i THINK i've just fixed this problem for me. I'm not dual-booting, but i was having the same problem just booting on Vista.

I changed the path of winload.exe and just rebooted without the Vista disc, and it seems to have worked.

OK - here's what i did (change the partition and identifiers to suit your circumstances)

C:\Windows\System32>bcdedit

Windows Boot Manager
--------------------
identifier {bootmgr}
device partition=C:
description Windows Boot Manager
locale en-US
inherit {globalsettings}
default {current}
displayorder {current}
toolsdisplayorder {memdiag}
timeout 30

Windows Boot Loader
-------------------
identifier {current}
device partition=C:
path \Windows\system32\boot\winload.exe
description Microsoft Windows Vista
locale en-US
inherit {bootloadersettings}
osdevice partition=C:
systemroot \Windows
resumeobject {77baf773-b959-11db-b80e-bb7df25a441f}
nx OptIn

Inside sys32, there is a "boot" directory, which contains winload.exe and winresume.exe, so i changed the path to make the bootmgr look there instead.

As i'm sure you all know, the command to change it is "bcdedit.exe /set {current} path \Windows\system32\boot\winload.exe" (- the "")

Hope this helps.
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Там же есть совет Divine Logix и, возможно, другие решения.