Olaolu from TX writes:
I received some mail in PDF format which keeps opening into notepad in characters other than the normal English, or not opening at all. How do I overcome this problem? I have tried PDF reader 9, 10, Adobe reader X, all with the same result.
Hi Olaolu, I replicated your problem and figured out the cause. It seems Windows thinks PDF files should be opened with Notepad. To rectify the situation, you need associate PDF files with PDF Reader. To do this, perform the following steps:
Step 1: Right-click the PDF file. The right-click menu appears. In this menu, click Open With and then click Choose Program.
Step 2: In the Open With dialog box, select Adobe Reader under the Other Programs heading. This tells Windows to open this particular PDF file with Adobe Reader. Notice that under the Recommended Programs, the Notepad application is present. This is because Windows thinks that all PDFs should be opened with Notepad. Let’s fix this.
Step 3: Now, you need to tell Windows to always open PDFs by using Adobe Reader. You can do this by selecting the Always use the selected program to open this kind of file check box. Click the OK button to save the setting and close the Open With dialog box.
You have informed Windows to open PDF files with Adobe Reader. To test the setting, open any PDF file. It will automatically open using Adobe Reader.
Here are some useful tips on file association with other versions of Windows:
- How to Choose the Default Program for a File 
- Controlling Open with in the Context Menu 
- File Association Options