I have found that the problem is with files in our libraries that contain a comma in the filename.
This is the header that is being returned:
HTTP/1.1 200 OK
Date: Fri, 13 Jan 2012 19:30:54 GMT
ETag: " "
content-disposition: inline; filename=ERDAS IMAGINE, ER Mapper and LPS 2011 System Specifications.pdf
Last-Modified: Thu, 30 Jun 2011 22:34:16 GMT
The problem is the comma in the filename (see "content-disposition" line). HTTP/1.1 does not support commas in the filename. I guess the latest Chrome update is now enforcing that rule.
My question now is, what can I do to remedy this in Sitefinity, other than renaming all of our downloadable assets that have filenames containing commas? Or is there already a fix for this that I can install?