I had troubles viewing and manipulating PDF´s in Safari browser.
After downloading a PDF document, and then fiddeling with buttons/options in the browser-window, I lost access to the document, and the browser-window froze.
Just the browser "return page"-button; where available. A reload of the document returned a blank page.
Adobe Reader manual did not give me fixes for this, so I turned to MacUpdate.
At http://www.macupdate.com/ I found 2 options resolving my problem;
"PDF Browser Plugin 2.2.3" and "Safari-Display or Download PDF files 1.2".
The former is really a treat. Both is free for personal use. I have asked the developer of the former one; where to donate. No reply from him yet. I will further that information if it´s possible, at this site.
I suggest all personal users of these plugins honour the developers.
These plugins, both fixes PDF-viewing-issues in Safari, and maybe other browsers.
"PDF Browser Plugin 2.2.3" has more options, but "Safari-Display or Download PDF files 1.2", fixes your basic PDF-view-problems.
Hope this info will be of use, for those stranded between mind, PDF´s, keyboard and screen.