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#11
Backup your PC and ...
Backup your PC and try running Winamp (or the other program) as Administrator.
Another thing you could try is to start the installer and then cancel it.
This often provokes Windows into offering to install it with the "Recommended Settings" (whatever that means).
Have you tried the Troubleshooting or Windows Program Compatibility Troubleshooter (in the Action Center)?
Do you have the correct output plugin selected in Winamp (Nullsoft DirectSound Output)?
I've been running Winamp since Windows 7 (b7048) with no playback problems.
It works on the 32 bit and 64 bit versions of Windows 7 (for me at least).
I switched to Winamp, after WMP 12 "savaged" the file names and details of ~900 of my mp3s (the very first time I tried it).