Boot problem, Minimal Bash-like, Ubuntu

Hello everyone,

First of all, I have Windows Vista 32-bit installed in dual boot with Ubuntu 8.10.
And so, big problem this morning when I turned on my computer: I discovered that the partition choice for booting does not display, but instead the error message “[ Minimal BASH-like line editing is supported. For the first word, TAB lists possible command completions. Anywhere else TAB lists the possible completions of a device/filename. ]” takes its place.
Needless to say, I searched every corner of the web to solve my problem, as mine is very specific.

To help you understand (maybe optional): Yesterday, on one of my Vista partitions, I applied formatting. The problem may come from there, considering that when I had Ubuntu installed in dual boot with Vista (from a live CD that I don't have with me), the person who installed it took a piece of that partition to free up memory space for Ubuntu (or something like that...). But after the formatting, I saw that this little piece of partition was still there, so normally no problem; I didn’t format that part.

In short, I have a big problem booting, I tried a lot of commands but sudo, ls... and the parentheses don't work with my minimal bash-like! So I was limited to a “find /boot/grub/menu.lst” which is the only command that gave me a result with some hope; it returns: hd(0,0)
Of course, since I cannot use parentheses under the minimal bash-like, I cannot exploit it...

I therefore ask you to help me with this problem, at least to be able to boot into Vista, where I have quite a few things to do...
Thank you in advance...

Configuration: Windows Vista Firefox 3.0.6