The codec allows you to preview the recording you just took. The recorder itself and the encoder both seem to work just fine, but when I try to preview a recording it says it can't find the codec. The codec is definitely there and in the same directory.
EDIT: I have tried reinstalling. It did not fix the problem. I am having the same problem on 2 other XP machines as well
EDIT: I tried re-registering the codec per Aaron's suggestion. The registration succeeded, but I still get the same error when I attempt to preview a recording
EDIT: After doing some more research, I was able to find a version of MS Expression 4 Encoder "without codecs." Surprisingly, this version works perfectly fine on Windows 7 with no errors, but the exact same installation produces the same errors I have already described when I try to preview recordings in Windows XP. How do I get the program to work as well on XP as it does on 7?