The problem is that PDF-attachments will not launch from my mail and
newsreader, Agent V4. Every other way of opening PDF files is OK:
doublecliking, in IE7, etc.
There seems to be nothing wrong with the settings in Agent, nor in Adobe
Reader (latest version 8.1.1).

What happens is that Agent extracts the file to the tempdir, and then
the following error occurs:

Adobe Reader 8.1 has encountered a problem and needs to close.
Signature of reader 8.1 error:
AppName: acrord32.exe AppVer: 8.1.0.137 ModName: acrord32.dll
ModVer: 8.1.1.20 Offset: 00174a74

When I click on that saved file in the temdir, Adobe launches and reads
everything fine.

After this I tested to launch MP3 files, error that returned was
AppName: wmplayer.exe AppVer: 11.0.5721.5145 ModName: mfplat.dll
ModVer: 11.0.5721.5145 Offset: 0000504d

JPG's, textfiles etc launch fine.

We have tried to let Agent launch a .cmd file with the text
cd /d D:\Temp
start "" %1
pause

Same error returns.
However - when I invoke that .cmd myself, it functions! Adobe loads the
PDF and displays it.
So - Agent can not invoke that .cmd, I can.

Looks like a security setting that prohibits apps to launch certain
files ...

Any help where to look further would be greatly appreciated ...