Check the network path. PDF files do not open only from network folders with DFS paths.
And everything perfectly works if in way to specify the server:
This problem is in protected mode of the program. That Adobe Reader X didn't give out more mistakes, this mode needs to be turned off.
1. Start Adobe Reader X
2. Go into Edit - Installations ...
3. In category choose the Basic
4. Take off the checkbox "Enable protected mode at startup"
5. Restart Adobe Reader X
Everything should work.
If the file does not open, then it means it is damaged. You will be able to recover it by using Recovery Toolbox for PDF
Look at this forum. There are tips on this topic. Maybe you will be helpful. Good luck!