GNU GRUB 1.97 BETA 4

i'm using linux ubuntu 9.10 since last 1month... from the very first day it told me to take update through update manager.today i had took the upload of all require security files which it had showed.but after that when the download & install was complete it shows me restart my computer & i did the same. but when my computer takes the boot n i choose "ubuntu" for run it shows----

"GNU GRUB 1.97 BETA 4"

& then it shows some message containing--------

"[minimal BASH-like line editing is supported.For the first word,TAB lists possible command completions. Anywhere else TAB lists possible device/file completions.]"

& then it ask for some command------

ch:grub>(asking command)

i couldn't understand what to do now & for this my computer has not been running...please help me..please...otherwise i can't started it.