Try burning the CD at a slower (preferable the slowest) speed. That often prevents burn failures, as well as reducing the frequency of corrupted burns that appear fine until you try to use them.
Adjusting Burn Speed in Brasero
In Brasero, you can adjust the burning speed by clicking Properties in the Image Burning Setup window (i.e., in the window that comes up right before the burn).
You can select a slower speed in the Burning speed drop down menu, near the top of the Preferences dialog.
You won't necessarily have the same options shown there, as this depends in part on your CD/DVD burner.
Adjusting Burn Speed in K3b
In K3b, you can adjust the burn speed in the same window where you tell it what image to burn.
Without more details in the question, this is likely the most effective solution that can be suggested for burns that fail to complete or are corrupted. It's often especially useful to reduce burn speed if you are at all unsure about the physical media to which you're burning, or if if you are burning a file containing data that will use most of its value if slightly corrupted (like computer programs, or an operating system).