Check the iso and CD
Get Lubuntu from GetLubuntu. A corrupted file download is not common but still we suggest that you check both the downloaded file for corruption and the CD for a bad burn before you report any problems with Lubuntu.
Check both at once with the "Check Disc for defects" (only on the Desktop ISO)
Check the iso file
On Linux systems: Start a terminal emulator e.g. LXterminal and type
You have to replace the path to the correct path, if it’s in Downloads change the command to
On BSD systems, including Mac Os X: Start a terminal emulator and type
On Windows Systems there are many freeware md5sum programs out there.
Then compare the resulting md5sum with the md5sum available from the Ubuntu servers. All md5sum for recent iso’s may be found in http://cdimage.ubuntu.com/lubuntu/releases.
Check the CD
1. On standard desktop (not alternate) CD’s when booting from CD you may choose “Check Disk for Defects”.
2. Alternatively you can create an iso
dd if=/dev/cdrom of=~/cdrom_image.iso
and check the iso with md5sum