Windows Media Player 12 won't play music CDs or even recognise a CD in the drive

I think this is a problem since I upgraded from Vista to Windows 7 but can't be sure. Basically if I put a music CD into my laptop drive, Windows Media player 12 not only doesn't automatically play it but when I open Windows Media no CD is recognised in the drive. But if I click on Windows Explorer the songs are shown (although won't play with WM). But they play with RealPlayer. This is clearly a WM problem then... all other CD/DVD functions are working, just not WM.

I followed the instructions below (from http://support.microsoft.com/kb/982116#nextsteps) and deleted two files from the registry as instructed but this made no difference. I also have run the Device Manager Troubleshooter for the drive and that didn't work. Also I tried Microsoft's Mr Fix it but that didn't either. Can anyone help me please?

Thanks

Richard
PS Obviously this means I can't rip CDs either!


(These are the instructions from http://support.microsoft.com/kb/982116#nextsteps)
Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
This problem is caused by two Windows registry entries that have become corrupted. To fix the problem, you have to use Registry Editor to delete the corrupted Registry entries. To use this method, you must be logged on to Windows as an administrator. Windows 7 or Windows Vista

1. Click Start
   
   , and then click All Programs.
2. Click Accessories, and then click Run.
3. Type regedit, and then click OK.
   
   If you are prompted for an administrator password or for a confirmation, type the password, or click Allow.
4. In the navigation pane, locate and then click the following registry subkey:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E965-E325-11CE-BFC1-08002BE10318}
5. In the right pane, click UpperFilters.
   
   Note You may also see an UpperFilters.bak registry entry. You do not have to remove that entry. Click UpperFilters only. If you do not see the UpperFilters registry entry, you still might have to remove the LowerFilters registry entry. To do this, go to step 8.
6. On the Edit menu, click Delete.
7. When you are prompted to confirm the deletion, click Yes.
8. In the right pane, click LowerFilters.
   
   Note If you do not see the LowerFilters registry entry, unfortunately this content cannot help you any further. Go to the "Next Steps" section for information about how you can find more solutions or more help on the Microsoft Web site.
9. On the Edit menu, click Delete.
10. When you are prompted to confirm the deletion, click Yes.
11. Exit Registry Editor.
12. Restart the computer.