Hi Tony, apologies for late reply - been away from home for a day.....
I'm not sure what is actually causing your problem - I've just tried to simulate your problem on my Windows 7 Laptop, however I don't have any Memorex discs. You mentioned a CD labeled 'AUDIO' - was this from a different manufacturer??

I placed a 'bog-standard' blank CD-R in the Laptop drive and this resulted in the 'AutoPlay' function starting, with the usual menu options : 'Burn an Audio CD using Windows Media Player' : 'Burn files to disc using Windows explorer' etc.
I selected 'Burn an audio CD using Windows Media Player' and the WMP window opened.
I then just looked for a random set of MP3 recordings in my Laptop's folders and dragged them to the appropriate area (burn List) in the WMP window and clicked on 'Start burn'.
The recording process started and when completed, ejected the CD-R.
I then re-inserted the CD-R and it played perfectly using Windows Media Player.........
The only thing I can suggest is that there may be some difference between Memorex discs and other manufacturer's discs so it may be worth trying another brand.

In the past, I have burned dozens of music CDs, both in .WAV and MP3 format, using many different brands (never Memorex or 'Audio' CD-R) and have never experienced any problems. I generally use a program called 'Ashampoo' for burning all my CDs and DVDs and found it to be a reliable and comprehensive utility.