have a Dell Dimension 8400 and loaded mint 17. all worked but had no sound. web site, not this forum, had me reload ALSA. Now video card is not functioning. When I boot off the hard drive I get a "too much work for IRQ16 and the screen goes black and the curser works.

when I boot off the CD I get a video test screen and no curser.

I can operate system off UBUNTU 10 from a CD. but it does not recognize files on the hard drive, meaning I cannot download them.

stumped, need help

Welcome to the linuxquestions.org forums! Are you new to linux, too? I'm almost as much of a newbie to the forums here as you, but I've been messing around with Linux Mint since the beginning of the year. So maybe we can sort this problem out.

You have a Dell Dimension 8400. The specs on the web say it has a pentium 4 3GHz cpu, 512MB of RAM, and an 80GB hard drive. Have there been upgrades, such as more RAM or a bigger drive?
Is the Mint distribution on an otherwise blank hard drive or is it dual booting with a Windows OS?
Does the drive contain data files that you want to save? In your position, I'd seriously consider wiping the Mint distribution off the drive and starting over. Backing up irreplaceable files would come first, though.

I assume that the final goal is to get this computer working with a linux distribution. Are you wedded to Linux Mint? Or would another distribution be acceptable if it was more friendly to your system? Do both sound and video operate correctly when you boot from that Ubuntu CD? If so, that might be a good choice.

Is your Ubuntu 10 CD the 14.10 distribution that came out late last year? Or is it a distribution that came out in 2010?

You wrote:
"I can operate system off UBUNTU 10 from a CD. but it does not recognize files on the hard drive, meaning I cannot download them. "
Just off the top of my head, did you mount the hard drive before trying to read the files?

correct on processor, but added 512 for total of 1 gig ram.

What do you mean by mount the hard drive first?
I played with the bios and finally that let me boot in "compatibility mode" Averything now works, but I had a couple crashes last night while reading articles in WIKI. I also lost all stored files on the hard drive. Somewhere in the process of putting LINUX back onto the hard drive I told it to partition the 500 gig hard drive into two 250 gig partitions and install the new Linux 17.2 in one partition. Didn't work as planned. The bios screens say I only have one 500 gig SATA and the Linux file menus are all empty. Is it possible the HD did partition and I'm just not seeing the other side. Not sure of what command in Linux would show me partitions.

A Dell Dimension 8400 with 1 GB of ram should be a good linux machine.

Windows will not read the Linux file system. I expect the bios will not, too. I think the drive was partitioned as directed and you are not seeing the linux side.

Playing with the bios should not be necessary. The computer should automatically show a menu with your boot choices.

Is windows in one 250 GB partion and linux in the other partition on the hard drive? Or is linux the only operating system?