I have several documents which I normally access via a symbolic link (NTFS, not a standard shortcut). These now give a permission denied error. If I access them using the UNC path, or if I disable protected mode, they work.
I am running Adobe Reader X, v10.0.1 on Windows Vista Enterprise 32 bit.
I also had this problem, running Windows 7 with Adobe Reader 10. I finally gave up trying to fix it, and went back to Reader 9, which solved the proble.
It's an issue with protected mode which is supposedly fixed in the latest Reader update.
Well, I just stumbled across this issue on Adobe Reader X 10.1.3. The bug is alive and well for PDFs stored on a local hard disk within a directory that's a symbolic link to another directory on the same local hard disk. Turning off protected mode does fix it, thanks for the tip. Judging by the list of fixes on the Protected Mode Troubleshooting page, protected mode was released as a mess of bugs and should probably just stay turned off until Acrobat XI is released...