My suggestion is to test the actual DVD disc that you burned in VirtualBox. Tell VirtualBox to use the DVD drive on the computer, put in the DVD that you burned and see if it works. You can also test the DVD on some other computer that has a DVD drive.

I also recommend running a memory test program such as MEMTEST86+ on the problem computer. I have seen really strange problems on computers that have a few bad RAM locations. In many cases the errors reported do not appear to be related to memory problems. A memory test program also tests quite a lot of the CPU and chipset.

Boot from some other operating system CD on the computer. If there are no existing files you can even try installing some other OS on the computer. If you can install another OS then the problem is more likely to be the DVD disc media. If you can't install another OS then look for problems with the computer or DVD drive.

You may have to ask IT to help you with some of the next things I will suggest.

Make sure that the disk controller and chip-set on the computer are supported by Linux. I have run into problems like this when the correct driver for the disk controller is not being used. That is more likely to be a problem with a SATA optical drive or a relatively new computer. You can use the "lspci" command in Linux to find the vendor and device IDs of all the hardware components.

Check the BIOS settings for the disk controller and drive. You may have to set the BIOS differently for the optical drive to work correctly. For example, you might not be able to get a SATA optical drive to work correctly if the BIOS has the SATA controller set for "legacy" or "IDE" mode.

If your optical drive and hard disk are on the same IDE ribbon cable, make sure that one is a Master and one is a Slave. Setting the drives for Cable Select doesn't always work right. The computer and the ribbon cable both have support Cable Select. When two drives on the same cable are not set correctly they can interfere with each other. A problem may not happen until the setup is copying from the optical drive to the hard disk. It's also safer to make the optical drive the Slave, as some don't work properly as a Master.

Hi,

I've experienced once a similar problem when I tried to install Slackware. It turned out, that the Computer was damaged, I don't know which hardware-component it was.

Another possibility to use the data on the DVD-image without the drive would be to mount the iso-image anywhere
and then select as source "install from a pre-mounted directory". This should work. It's of course necessary, that you have any partition where the iso-image is stored an which is not formatted while the installation.

Markus

Well, in my installations in the past years I have always started by the ADDSWAP step, then the installer goes thru each step only once and without issues.
But before I realized that ADDSWAP has to be first, I had the same issue for each and every installation: the installer will fail to detect a slackware disc if it has to try a second time.

I would suggest to try the 'pre-mounted' option, or just exit the installer, and then start it again and check ADDSWAP first.