It sounds like (remote support mode on), like the side-by-side installation is causing some issues. Windows may be interfering with the MBR that Ubuntu is trying to update with GRUB.
That being said, my kids' machine has Ubuntu installed by itself. My eldest (11 years old at the time) originally installed 8.04. Just a week or so ago, I used the Update Manager to upgrade it to 10.04. Everything went smoothly.
I never install Linux on the same hard drive as Windows.
I have a separate 40gig drive devoted strictly to Linux (Mint).
What I don’t like about Linux, is every time you want to access something on the drive or even do updates, you have to put in your password.
Too much of a pain for me. So I just run WinXP.