If you received an error "There is a problem with Adobe Acrobat/Reader. If it is running, please exit and try again (xx:xx)." in Windows XP/Vista/7 and using Adobe Acrobat Reader X, just simply:
1. Close your current IE browser and open Adobe Acrobat Reader X
2. From the menu select Edit - Preference - General
3. Uncheck mark the option for Enable Protected Mode at startup
4. Click "Yes" if you are prompted to “manually restart the application”
5. Press "OK" to continue
6. Exit from Adobe Acrobat Reader X and open your browser again
7. Try to preview or load the PDF files again
If these steps still not working, uninstall the Adobe Reader X with a lower version (9 or 8) or try using another free PDF reader such as FoxIt Reader.