Ok ... Do you have Fedora 7 installed now ..? If so you need the upgrade disk instead.
I recommend the LIVE version, then install from there.
Now I just downloaded the Fedora 11 Live cd and booted in my VirtualBox. There is a countdown so I pressed the down arrowkey. Then there was a menu:
Verify and Boot
Boot from local Drive
These are the options I was referring to earlier in the in post. Boot to the DVD and choose the "Memory Test" from the menu. This will run tests on your installed system RAM. When finished, hit the ESC key and reboot. If there are memory errors then you should retest a couple times more to ensure that the memory really is bad.
Second, after the memory test, and you've rebooted. Go back into the menu and select "Verify and Boot" This will verify that the disk you burned from the downloaded ISO image is correct and verified, and is not corrupt. If the check fails, then you need to re-download the disc, burn it at 2x. Then reboot and Verify the disc in the same manner.
Steps to take, Boot the DVD. Enter menu
1) Memory Test
2) Verify and Boot
Then if any errors on the memory, try again twice more to confirm bad memory. If any errors on the Verify and Boot, then re-download the image and re-burn at a slow speed