I get an error message when I try to open wav files that I have Eq’d with Har-Bal in Wavelab 4. I get a message that the audio compression driver is not a compatible format. I use Wavelab first, then Har-Bal and afterwards Wavelab will not open it.

This is a known issue in the LIBSNDFILE library that is to do with the ambiguity of some WAV file formats. In particular floating point formats. Basically what happens is that HarBal reads in your 24 bit float format and reports a bit depth of 32 bits (which is not the real bit depth). When it creates a compatible file format it ends up creating a 32 bit PCM file. You can avoid this problem by either using a 24 bit PCM (integer) format or a Type 3 24 bit float format.