What are the full specs.of the "problem" WMA. WMA's can have a lot of different settings and "stuff." Knowing how that one differs from the "good" one, might be the key.
Like MP3, WMA will (probably) have to be conformed on import--conforming essentially creates an uncompressed, 32-bit floating point PCM version of the sound file. What likely happened is that was interrupted or otherwise went wrong, so PPro is not able to playback the CFA file correctly.
Best bet is to close PPro, find the CFA file (and perhaps PEK file) for the WMA (the location of the CFA will depend on how you have your Media Cache settings set up), and trash them. Relaunch PPro, and let the audio reconform. Test, and report.
What was happening is that the file was not conforming. It would not even play in Auditon correctly.
I opened the file in an audio editor and saved it in a wave file format and it now plays fine. When I im
ported the file, CS5.5 conformed the file. The previous version was not conformed by CS5.5.
Glad that the WAV is working for you.
As mentioned, WMA's can have a lot of "stuff" in them, and not all of it is mainstream "stuff."