Upgraded the kernel today and got an error

[savyasachi]

Hi all ,I am a newbie to linux ,so please help me out of this sticky situation.(Ubuntu 9.10)Today update manager notified me to update and i updated to a new kernel version and i restarted the system and selected the new kernel to boot .But it just restarted.Then i tried the recovery mode,then also the same thing happened.then i chose the previous version and it booted without any problem also now when i check for updates the update manager shows the following message

[gg234]

Iy you have any third party repositories added to your sources.list file delete them and check

[savyasachi]

Still the same result

[joe12]

hi i have the same issues with the update error its  because  the key is no longer valid for the ppa   i ll find the right one
update :
open up the terminal and type  sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 86E80C6B7

[joe12]

 and as for your kernel what version did your update to ?

update:
if you updated to something ending in 18 stick with the old one
 tell me is the update error is fixed

thanks