From a totally novice a small question and a big congratulations.

Thank you very much, Great Program and Great People. This was so fast. My faith to Mankind is slowly been restored
Costas

The 16 generic and the 15 generic correspond to different kernels that are installed on your system.
When you first installed Ubuntu, it probably installed the "15 generic" kernel, and then, during a system update, the "16 generic" version was added.

For safety, the older kernels are not replaced in case there is a problem and you want to revert back. If you want to remove "15 generic", you can

1. Start Synaptic Package Manager (System/Administration/Synaptic Package Manager)
2. Perform a search for "linux-image"
3. You should get a list of packages. Of those, the ones that have a dark green box at the start are packages that have been installed.
Verify that both linux-image-2.6.20-15-generic and linux-image-2.6.20-16-generic are installed.
4. To remove the older kernel, select linux-image-2.6.20-15-generic, right-click and choose to Mark for removal. It will ask you if you want to remove an additional package (restricted drivers), click Yes.
5. Click on Apply to apply the change. The older kernel will be uninstalled, and the entry will be removed from the boot screen at the start.

This change is quite invasive, and it is important to make sure that one kernel is at least installed.
I just removed generic-15 from my system and it is ok for me.

An alternative procedure is to simply remove the menu option for the older kernel, thus avoiding to uninstall the package. Please ask if you want instructions on this. The file to edit is /boot/grub/menu.lst

The "recovery" option has special functionality when the system fails to start. It is ok to have. If you wish to remove, you would need to edit /boot/grub/menu.lst as well.

Sorry to be back, I just tried it and after my password was entered I received the following message:

Authentication Rejected, reason : None of the authentication protocols specified are supported and host - based authentication failed.

Also the menu.lst (/boot) gedit appeared with nothing to show. I open file and then grub, there were no config files there. There were two config files in the boot section. I opened the one related to generic 15, it is a long file with many #s. I did a search for title and nothing was found. So I closed every thing and left is without saving. Too scared to try something than may lock the whole thing. I would rather live with the long startup screen.

Thank you very much anyway, it was wonderfull experience.
Costas

Hello Simos, you must be Greek too. As I said I am totally green in Linux and Ubuntu and I am afraid to change anything. If it is not much work I will appreciate some details. A strange thing happed in the last few minutes. After my unsuccessful attempts to change the boot list from the menu.lst, I did a restart of my computer. It went on BIOS in safe mode because it found a problem with my CPU speed. It gave me only two choices 2000 Mhz and manual. Decided to take the manual since my computer is only 533 Mhz. It started properly only this time what was 16-generic become 15-generic. So I am glad I did not delete it. But if there is a way to deactivate it I will appreciate that.
By the way I live in Toronto Canada, where about do you live?
Best regards
Costas

I get that error too. Not sure why. It still opens and allows me to edit though. If it opened a blank document it is because something wasn't typed right. Make sure the path looks exactly like this:

gksudo gedit /boot/grub/menu.lst

Anything different (even one letter) will open a new document with the new name.

@Costas, Jim: The error "Authentication Rejected, reason" can be ignored. I am not sure why it appears. The file /boot/grub/menu.lst was opened successfully as administrator and can be edited. I believe Costas that you saved the file, that's why you did not get the extra lines in the boot menu.

The easiest route to remove them (if you prefer to do so) is to remove the old kernel package as I show above, using the Synaptic Package Manager. I tried on my Ubuntu 7.04 and it was fine for me.

When you edit system files it is important to keep a backup copy of the original file. In this way you will be able to revert back to the original version.

To take a back-up, you can use "gedit" (the text editor) and save a copy of the original in your home directory. Then, close and run again "gedit" to make your changes.

If you want help with the current state of the menu.lst file, you can upload it to a website such as http://ubuntu.pastebin.com/ and paste here the URL. (pastebin is a website that allows to upload short text files and provides a unique URL that you give to others so they can view that text file; any files there are visible by all).

@Costas: I live in Athens.

Hello Simos, Jim, I did not save the file after opening menu.lst I definitely closed it without saving. The only difference I have now is that what was before 16-generic is 15-generic and vise versa. I will live with that until I get more comfortable with linux and then I will delete it or at least hide it as Jim suggested (if only I can find the appropriate line to add the #. For now I am done with this minor problem. Sorry for taking so much of your time. You were both very encouraging and provided great help.
Simos, I do visit Athens almost every year, I am so sorry about the fires.
Best regards and many thanks to both
Costas

Thanks Jim Hutchinson, that solved my question.