Check the iso and CD

Get Lubuntu from GetLubuntu. It is very important that you check both the downloaded file for corruption, and the CD for a bad burn.
Corrupted file downloads are less than common, but we insist you check your downloads before you report any problems with Lubuntu.

1. Check both at once with the "Check Disc for defects" (only on the Desktop ISO)

or

1. Check for file corruption with md5sum (see below) or by using BitTorrent (automatically checks for corruption)

2. Check that the CD Burning utility verifies the burn. More info here or check the burned CD (see below).

Check the iso file

On Linux systems: Start a terminal emulator e.g. LXterminal and type

md5sum /path/to/lubuntu*.iso

You have to replace the path to the correct path, if it’s in Downloads change the command to

md5sum ~/Downloads/lubuntu*.iso

On BSD systems, including Mac Os X: Start a terminal emulator and type

md5 /path/to/lubuntu*.iso

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. E.g. for Lubuntu 12.10 (Quantal Quetzal) the md5sum is in the file http://cdimage.ubuntu.com/lubuntu/releases/12.10/release/MD5SUMS

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