For some reason, I don't know why, there are times I am not "allowed" to copy anything. Then I have to reboot a new browser, and then I can copy. (Definitely a browser problem.)
That usually happens on the google-cached version of PDF documents. I've had it freeze up my computer as well.
Instead of trying to copy from that version, click on the home link at the top of the page and copy from the original document.
spybot search and destroy....free and reliable.
http://www.download.com/Spybot-Search-Destroy/3000-8022_4-10401314.html?tag=lst-0-1