here's another potential cause I found on a newsgroup....
Struggled with this, and found a fix, that I'd like to share (if
nothing else for people with this problem that may refer to DejaNews)
The problem I had was related to Microsoft ADPCM. Apparently Cakewalk
needs this to be enabled to be able to import wav files, I had it
disabled, for God knows what reason.. this took me a while to find,
needless to say. (The error message is less than informative.)