I have an Intel Core 2 Duo system, and I was experimenting with running different Linux live distributions on it. A while back, the video card went bad on the computer. I didn’t know what was wrong so I took the system into the place where I bought it. They replaced the video card. Even though the computer will boot the operating systems I have installed on the internal hard drive. I cannot get it to boot live distributions successfully anymore.

I tested the live distribution I currently have by booting from it on another system and it booted successfully, so I’m pretty sure there’s nothing wrong with the thumb drive I try to boot from. When I try to boot off of the thumb drive on my system, I get a menu to select how I want to boot, and then some text scrolls across the screen and eventually the output stops and the computer just sits there.

I’m not sure how relevant it is; here is an example of the last few lines that appear on the screen when I try to boot:

[ 9251752] sd 10:0:0:0: Attached scsi generic sg4 type 0
[ 9251974] sd 10:0:0:1: Attached scsi generic sg5 type 0
[ 9313567] sd 10:0:0:0: [sdd] Attached SCSI removable disk
[ 9317564] sd 10:0:0:1: [sde] Attached SCSI removable disk

I don’t know if this means there might be some other problem with the system, and I should take it in to get looked at again, or if there is some other way to solve the problem.

Does it have a liveboot failsafe in the menu?

I do not remember seeing any option for a fail safe. The distribution was Kubuntu 13.10 made using UNetbootin.

I find Unetbootin to be quite buggy, it works sometimes.
I have never had difficulty with dd.
My advice would be to copy Kubuntu 13.10 onto the usb with dd instead of unetbootin.
Once you have done that give it a try and let us know how you go.

Like I said. I already tested this on another system and it works fine. It seems that what I made UNetbootin should work. Also, when I got the system back I tried booting a live image I had of Linux Mint 17 that used to run fine and didn't boot anymore. I think it behaved the same as the Kubuntu I'm trying to use now.

I suspect the problem is with the computer and the live distribution.

I know what you said and that is why my reply was what it was. Unetbootin works "sometimes".

If you have burned a cd/dvd and that cd/dvd worked on that machine previously it isn't the live distribution but it could be hardware breaking down and not working as it should anymore.

If it did boot to a usb at one time and we assume the usb is good then try this.

Power off.
Remove ac plug.
Press power button a few times.
Install bootable usb stick.
Boot to bios.
Does usb show as a hard drive choice? If so then move it in the order. (notice I never said anything about usb, I said hard drive)
Then try to boot with hard drive as first choice and usb above the internal in hard drive order.

I can boot to the bios and configure the computer to boot off the USB stick instead of the hard drive. That is fine, and when I boot off the USB stick I get to a UNetbootin menu with options to choose from. What doesn't work is selecting the option to actually boot into the live distribution after that. When I select that from the menu system some text scrolls on the screen related to the boot process. There does not seem to be any error messages. However, the boot process just halts with text left on the screen and nothing else happens.