I have the same problem with Opening WAV files in Wavelab 5.
This started when I upgraded my O/S to Vista Ultimate a few days ago.
There are no errors reported, the program just closes when I attempt to open a WAV file. Another thing to note is that I am able to record successfully in Wavelab. I can even apply effects and render them, BUT the program shuts down when I try to save the file.
When running XP Pro, I had no issues. I'm wondering if it maybe something to do specifically with the Vista O/S. Looking for solutions at the moment to get it working...
OK, after a LOT of searching, I've found a solution for Vista users.
First off, you must set Wavelab to start in Compatibility mode (xp sp2) for this fix to work.
I can't post the link, but do a search for R a P I d S h A r E Wavelab Vista Fix on G00gle ;-)
It's worked for me, so good luck to you ;-)