Saw your problem and wanted to see if your problem only occurs on Win7, but I can (happily?) report that XP SPIII returns the following error:
Could not start the Dibbler - a DHCPv6 server service on Local Computer.
Error 1075: The dependency service does not exist or has been marked for deletion.
After seeing that error, I would suggest to use a tool that checks for (static and dynamic) dependencies like 'Dependency Walker
' (freeware, portable, runs on XP and higher).
On my system DW said that the msjava.dll was missing in the dibbler folder. Got that one from the net and used the Dependency Walker again.
Now the following error was returned by DW:
Warning: At least one module has an unresolved import due to a missing export function in a delay-load dependent module.
and the icon from 'mpr.dll' is colored red(-dish).
Hope it helps.
Alas, my brain starts to succumb heavily to the charms of the (mighty) mistress called sleep. However, I think that with DW you'll get a better idea of why the service is failing.