Here's a summary of my equipment: 2005 Macbook Pro 2,2; Intel Core 2 Duo; 2.16 GHz processor speed; Disk Driver: Mat****aDVD-R UJ-857D.
I tried blowing out the DVD/CD with canned air as suggested and re-tried burning a disk. It acted like it was working until it got to the final phase of "writing" and then seemed like it got stuck in a loop with the drive making that humming noise, stopping, humming noise, stopping, etc. I finally tried ejecting the disk which it finally did after numerous attempts.