I have a clean install of 7.3 at a hosting company (PowerDNN) and file crawler is broken there. 

That server is a Windows Server 2012. I have it working locally on a Windows 2008 R2 server. Both have Adobe iFilter 9 for 64 bit. And both have 32-bit set to false in the App Pool settings.

So it is something to do with either the OS, or the way PowerDNN configures it.
But Server 2012 is one of the recommended platform, so there must be some weird setting, right?

This is the error I now get in the 7.3 empty site:

Search: File Crawler
Scanning for files changed since: 6/21/2014 10:07 AM
Error indexing pdf document using iFilter (Possibly password protected.): 2000-01.pdf