Solution given by Lepikk worked for me.
Just for completeness, I've used a cd-rom of Ubuntu Karmic Beta1 and from the option I've choosed "restore damaged installation" or something like that.
Than I've followed the wizard and when asked I've launched a console shell with /dev/sda1 (wich is my root filesystem) mounted.
And here I've inserted the grub-editenv command given by Leppik.
Solution given by Lepikk worked for me.
Just for completeness, I've used a cd-rom of Ubuntu Karmic Beta1 and from the option I've choosed "restore damaged installation" or something like that.
Than I've followed the wizard and when asked I've launched a console shell with /dev/sda1 (wich is my root filesystem) mounted.
And here I've inserted the grub-editenv command given by Leppik.