ubun2^beta

I upgraded to Ubuntu 10.04 and now my computer won't start. At first it did but after the last restart it did not boot. It does not show any boot menus or anything. How do I go about booting it from a CD? What do I do afterwards? Thank you very much.

Ok.  Bare with me a second.  Here's my partition scheme;
(200GB)/dev/sda1  /boot  500M/dev/sda2  LVM    100G

• / (root)
• /home
• /tmp
• /usr
• /var

/dev/sda5  swap 4G
 

Just downloaded moblin 2.1 image file and thinking of installing it in my ACER aspire one netbook.
 
Since it is .img file i don't know how to burn or flash it into as a bootable USB flash drive so that i can boot my netbook with USB and install moblin. Please help