This appears to be a common problem. I've found several mentions of it in the forum, but the conditions are different in every case, so I can't tell which ones (if any) reflect the same problem. And so far I haven't found any suggested solutions.
I'm having problems using the PDF filter with Windows Explorer's file search function in Windows XP.
As I understand it, there are three versions of the filter: a current one for 32-bit systems that is distributed with Adobe Reader; a current one for 64-bit systems that is downloaded separately; and an old one (version 6) that is downloaded separately.
I have the old one installed and working... sort of. It finds some files but misses others. I don't see any pattern in what it finds and misses.
The obvious first thing to try is to install the new filter. But there seems to be no way to do it. I'm running 32-bit Windows XP Professional, so I need the 32-bit version. But the instructions on Adobe's web site say to use the installer that comes with it, but (in Adobe Reader X) there is none.
How can I solve this problem -- by installing the current 32-bit version of ifilter, or by any other means?