Dual boot problem with Ubuntu 10.10, but Vista boots OK

It looks like you have a mix of a wubi install and a migrated Ubuntu install. It's unclear what you are or were booting. Did you run LVPM at some time in the past? (It doesn't work on recent versions of Ubuntu). Did you ever boot Ubuntu direct from the grub menu before the upgrade, or did you always select Windows and then boot Ubuntu (the wubi ubuntu) after that? Which Ubuntu did you upgrade?

Run the bootinfoscript (http://bootinfoscript.sourceforge.net/) and paste the results to
http://pastebin.ubuntu.com/ and then the pastebin address back here.

I have used the ubuntu 9.10 previously, and don't remember anything about running LVPM...
With the ubuntu 9.10, I booted directly from the grub menu, and if I booted windows,I didn't get the windows bootmanager menu.
After ubuntu 10.10 installation, I now have both the grub menu, -and the wubi (windows boot manager) menu... Seems like I have got boot parameters in the shared ntfs partition (sda3) after the installation.
http://pastebin.ubuntu.com/542646/

Should I remove the bootinfo from sda3 (wubi)? -How to?

You have some sort of remnants of Wubi, but the virtual disk (root.disk) and swap file are missing. If you didn't delete them then perhaps they have been moved e.g. windows sometimes removes corrupted files. It doesn't look like you ran lvpm, but I thought it likely as it uses ext3 instead of ext4 as well as the wubi clue.

I am a little unclear about what you've done. You said you upgraded to 10.10, but your Ubuntu install only has one kernel in grub. Usually when I upgrade I see a 10.04 kernel as well.
Did you ever boot it after the upgrade?
When you were previously able to boot Ubuntu, did you boot it via the grub menu, or did you first select Windows and then select Ubuntu a second time? (That's the Wubi install you are running the second time)

The reason for only one kernel in the grub, is formated partition...
I previously had 9.10 version on the sda6 partition, with ext3 and same partition size. Nothing changed on the other partitions as well. But, since I didn't have internet connection on the computer at the time, I downloaded 10.10 to another pc with windows, and burned the .iso image on a cd.
I first tried with the "ubuntu-10.10-alternate-i386.iso" cd image, and during installation of that one, I performed a format of the sda6 partition during the installation process. Formated as primary partition, ext3, and mount point = /
I got the problems with booting after that, so I tried to install the "ubuntu-10.10-desktop-i386.iso" after booting the pc with the cd and installing with the graphical interface. (Didn't format the partition this time! -Should probably try this in case something went wrong the first time...)

However, at the moment I'm reading the http://ubuntuforums.org/showthread.php?t=1639198 and see that I have a rather similar problem as "Problem #2", except that I didn't actually upgrade the normal way, but formated the partition and installed 10.10 on a "clean" partition.

Thanx for the excellent help!

That link is for wubi installs so won't relate to your clean install on /dev/sda6. If your fresh install doesn't boot, then there could be a problem with your hardware... have you tried running 10.10 from a live CD? It's a quick way to check whether your hardware is compatible. You could also try adding nomodeset to your boot options: http://ubuntuforums.org/showthread.php?t=1613132

If it's a hardware issue, then installing wubi won't work either. It's strange that your grub is obviously fully functional on your new install (/dev/sda6) as you're booting windows from it. So likely it is a graphics card issue or something similar.

Personally I think you should forget installing from Windows (wubi) and just focus on getting 10.10 booting. Or... since it's a fresh install, just drop back to a version that worked for you before - I assume 10.04 worked fine...