>installed the K-lite codec pack
So sad... codec packs sometimes/often change the priority of how codecs are used, resulting in nothing working very well
I have read other messages saying the only way to fix those kinds of problems is to completely wipe the hard drive and install everything new
Then, when an individual file does not work, use something like the free http://www.headbands.com/gspot/ to find out what is really needed, and then find just that codec to install
Read Bill Hunt on a file type as WRAPPER http://forums.adobe.com/thread/440037?tstart=0
What is a CODEC... a Primer http://forums.adobe.com/thread/546811?tstart=0
What CODEC is INSIDE that file? http://forums.adobe.com/thread/440037?tstart=0
It sounds as though you have only installed K-Lite recently. I suggest that first you run the K-Lite uninstaller and then use the Windows System Restore feature to roll-back prior to the K-Lite installation. That way you should be reasonably assured that there are no remaining remnants.
Insanity is hereditary, you get it from your children
Also, as K-Lite normally also installs FFDShow, which has caused a lot of grief with several Adobe programs, I would look at removing it too. In the past, it was listed separately in Add/Remove Programs.
As for your AVI files, I would first look at them in G-SPOT to see just what is in them. John T. has linked to the "AVI wrapper" article, which will give you a lot more background.
As for the Importation of the WAV files, are you allowing them Conform? That process can take a while, based on their Duration and the speed of your computer. Also, if they are 48KHz 16-bit PCM/WAV, the time to Conform, will be reduced to the minimum. What are the specs. that you converted the Audio files to?