New Document denied access

I purchased and downloaded a document from ansi.org last week. As soon as I tried to open it with Reader, I got a message that said "Document Access Denied - You have already registered your quota of machines". How is it possible to deny access to something that I paid for and downloaded to only one computer? I have spent hundreds of dollars over the last few years downloading duplicate copies of documents because Adobe will not allow me to access the copies that I already paid for. How do I gain access to the documents on my hard drive?