Kubuntu 8.04 2.6.24-14 and -15 don't boot

[Blue Rose]

Hey,
I got some update last few days, kernel changed to 2.6.24-14 and later 
2.6.24-15.. but those two will not boot properly. I get some weird 
prompt screen in which I got no clue what to do.. so I reboot and select 
2.6.24-12 in te grub menu, which works fine.
Anyone else has this too? Should I do anything with that or not? (bug 
report or so?)

cheers
Linda