Can't copy file to disk

I've read numerous discussions here about this problem but haven't found any problem-solving answers.

My computer is a 21.5-inch iMac (from 2011) using the OSX Lion 10.7.5 which came installed on the computer.

I am trying to copy a folder from the hard drive to a CD disk. The folder is pictures in JPG format and is 5.2 MB. The disk I am using is a new Memorex CD-RW with a capacity of 700 MB.

1) I Click "Burn to disk"

2) It tells me to insert a blank disk and name it, then click "Burn"

3) I get the progress box showing the data is transferred and verified, the box goes away, the CD drive runs for a while, and the CD shows in my "devices".

4) I open the CD while it is still in the computer and see that all the files are there. It shows the date modified and that there are 6.2 MB of data on the CD and it is "read only".

5) I eject the CD.

When I reinsert the CD, it shows up on the desktop as an "Untitled CD" that is blank. Shows date modified, zero items, 6KB.

I have tried other new CD-R and CD-RW disks and get the same result.

A year ago I successfully copied a files to a CD. I ejected and reinserted the CD and the data was there at that time. When I insert that same CD now, it shows to be blank.

(I can play prerecorded DVDs and music CDs fine.)

So, the question is: What happened in the last year? Is there something wrong with my CD drive, and is there some sort of diagnostic I can run to find out?