Error message on opening .pdf documents

I’ve received an email with a .pdf attachment. When I click on the attachment I get two options, open or save. I read here, on the FAQ section, where I needed to double click the attachment. I did this, was offered the option to ‘not show this again’, but still get the error. It’s an interesting message that ends saying “Attempted to divide by zero”? I did go to the computer settings and verified that I do have a default program selected for opening .pdf documents; I"m using Windows Reader. I’m downloading Adobe reader now and I’ll try that . Any ideas on the error messages…?