You could be low on resources, try rebooting and then open your PDF file. It could be a large file causing the already hot computer to overheat and freeze.

How long since you went inside the case and cleaned out the dust bunnies?
How old is the computer?
How much RAM (memory) do you have?

Alright. I went to my documents and found three pdf files.
Is that what you mean?

OK so can you double click on any of those 3 PDF files and open them?

Perhaps you could provide a link to the PDF file you are trying to download so we can see if it opens for us.

What about my questions I asked above?

Let's clarify something -- the freeze happens when you try to download a .pdf file from an email or the internet, right? Not when trying to open one that is already on your computer? If that's the case, how long have you waited before deciding the computer is frozen? I've downloaded a few large .pdf files that have taken a LONG time even though I have a high speed satellite connection. As soon as I click to download, the computer just sits there and nothing else happens till the whole thing has downloaded, sometimes several minutes if there are a couple hundred pages. Once they're saved on my computer, they open instantly no matter how large the file.

Is there any chance you're experiencing the same situation but not waiting long enough?

also make sure you have all current critical updates to Adobe reader or what ever pdf reader you are using because there are some serious infections going on with pdf files due to needed patches not being applied, the best way to make sure you are updated is to use the secunia tool
Secunia Online Software Inspector (OSI)

download the pdf file to your pc then before opening it right click on it and choose to run your antivirus scan and malware scan on the pdf files, much safer to do it that way than to simply open in browser.

owbist, Yes, I could open the files and they are deleted. I still have 73% of memory left. This computer is about five years old.
silvervista, Yes, the freeze occurs when clicking on a link over on the garden forum, then a box pops up and says a problem has been encountered and has to close.
ravencajun, Yes, I tried to update the Adobe Reader, but was stopped and asked to clarify something, then a box popped up saying "Critical Error". AAAArg : (

Thanks all for pointing me in the right direction. Updates fixed the problem : )

Tnx. for the reply on not waiting long enough. I didn't. I reloaded the reader and same results untill a minute or so later it came through. I guess I should have checked the little red light for blinking. Grady