First, apologies if the answer to this is only a Google away. I tried, honest I did. But I wasn't able to find anything about this problem posted elsewhere.

I'm using Adobe Reader v9.3.2 in Windows 7 Home Premium 64-bit. If you want more system details, then just request them.

What happens is that when I attempt to open a PDF by clicking "Open" on it then (1) adobe reader never opens and (2) the explorer.exe program is (apparently) recursively opened. I base this on opening the Task Manager and seeing a long list of explorer.exe processes under the "Processes" tab. Usually there is only one. When I recreate this problem, the list of explorer.exe processes are at least a page or two long. (Too many to bother counting).

I "correct" this problem by logging off and then logging back on. This kills all the explorer.exe tasks. Unfortunately I don't know another way to terminate them all.

Now here's the curious part. This only happens when I attempt to "Open" a PDF file. If instead I use the context menu (right mouse click on the PDF) and select "Open with" and "Adobe Reader 9.3" then Adobe Reader opens the file with no problem.

It seems that there is something wrong with the setting for the default open action for PDF files. However, I have been unable to fix this by changing the Windows setting. Here is what I have tried.

1. When I open Control Panel > All Control Panel Items > Default Programs > Set Associations I do not find an entry for file type .pdf. There are only entries for .pdfxml and .pdx.

2. When use "Open with" on a PDF file and select "Choose default program", the check box for "Always use the selected program to open this kind of file" is disabled (greyed out).

I have uninstalled and reinstalled Adobe Reader but the problem persists. While obviously no lives are at stake here, this problem is annoying the frickin' heck out of me. If I forget and recreate this bug then I have to stop everything I'm doing to stop it.

Any suggestions on how I might go about fixing this?