I repeated your test with a 5D CR2 and what I found is that it worked perfectly unless "byte order" on the TIFF save options was set to "Macintosh".  As soon as you set the byte order to "IBM PC" it works fine.  Can you confirm that's the case on your system as well?  Not sure why Adobe would set "Macintosh" as the default when they know their software is installed on a Windows system, but it does seem to have the wrong default.  I may have to disable IPTC if Mac byte order is selected if I can't find an update to the third party IPTC tool I'm using that will allow Mac TIFF's.

Mike

Byte order doesn't seem to matter for the image itself.  Not sure why it makes IPTC a problem for QU.  I'd have to look into it further, but I do know that Adobe does some non-standard things with IPTC.  Last time something similar happened I caught Adobe putting Unicode text into IPTC data.  Fine for them maybe... but it (badly) breaks the IPTC standard by inserting what amount to non-ascii control codes.  They seem to be fine with arbitrarily "redefining" standards.  I guess they figure everyone will follow.  But again, I'm just guessing at this point from what I've seen in the past.  I'd have to look into it when I have more time.  Right now, I'm busy with QU 2012 which is due out by the third or fourth week in August.  

Mike

referring to http://www.iptc.org/cms/site/photometadatasupportlist.html?channel=CH0101#70 and other pages on iptc.org, you can see how various software packages comply? with the so called standard. iptc have based much of what they do on what Adobe does, so of course Adobe can behave more or less as a law unto themselves, the rest have to play 'catch-up'.

Best wishes,

Ray