I've wasted four successive CD-Rs, same results every time.
The CDs are Maxell ones, which are one of the most respected brands, plus in the past I've used them without problems.
Also, a minute ago, the internal CD drive was reporting "Drive not ready (medium not present)" for any CD, I had in it. I then rebooted the PC and the drive started reading CDs again.
I also have an external USB CD.DVD drive, and that is now reporting "Drive not ready "spindle servo error" regardless of what type of CD is in it. Seems a bit of a coincidence that both the internal and external drives should fail at the same time, and I'm wondering whether it could be something more deep seated?