GRUB problem after upgrading to 10.04

[user1]

>> today I have upgraded from 9.10 to 10.04. At the end of the upgrade
>> process GRUB-pc has been installed. I chosed /dev/sdb1 as device and my
>> pc does not boot up anymore.
> 
> https://help.ubuntu.com/community/Grub2 - Reinstalling GRUB 2
>  - SIMPLEST - Copy GRUB 2 Files from the LiveCD
> 
> should get you back on track.

I have on my harddisk:
8.04 (grub)
9.04 (grub)
9.10 (grub2)
10.04 (grub2)

I am using 9.04 even after installing 10.04 - I tried both alternate and 
desktop installs and got same grub2 problems, namely that grub2 does not 
see my other operating systems on my harddisk.

Now I can only get 9.04 to boot and see no boot menu any longer.

So I am forced to use 9.04, and it seems as I am using grub as bootloader.

I find reading the internet that grub2 is under strong developement and 
not really ready for use.

I therefore think one should use grub instead of grub2 until grub2 is 
really ready and stable to use unless you are a super user.

My intention was to use 9.04 until I got 10.04 really set up and working, 
so I could easily switch between the two.

Note: grub is "grub legacy = old grub" and grub2 is "grub2 = new grub"