Firefox3 error (RelaunchUsingCreateProcess::CreateProcess failed)

On XP-sp2 I've had success with Firefox 2.  But when I try to ThinApp Firefox3 I get an error when I launch it:

I have even tried Thinstall v3.382.  Also I've tried various things such as ChildProcess "External".   I'm not sure what this error relates to, when I googled the error, I see a couple of references to Vista, but this is XP-Sp2.

Any thoughts?