Good evening
Did you have any luck yet.
Here are some items you can check that might help narrow the issue down / help you.
#1. Right click on a PDF and goto properties and make sure it says it is a PDF and has the adobe PDF icon in the middle of the PDF
#2. Are you having any other issues, pc running slow, MS windows errors etc
#3. (this more of a question) What OS are you using XP, Vista, Windows 7 ect
#4. Do you have the regular adobe reader and if so what version 8, 9, 10?
Hope to here from you soon, Mike