Same problem here. SharePoint 2010 with Win 7 64-bit workstations, Adobe Reader 11.0.0 / 11.0.3 and Adobe Pro 11.0.0 / 11.0.3 and Internet Explorer 9.0.15.
We can browse to a .pdf file in SharePoint and get the
"The URL you have provided could not be reached. Please verify that the URL is correct and that the network location is reachable."
Microsoft AND Adobe have been contacted for tech support and both hooked me up with techs that continuously go back to "support teams" to get questions to ask me. In 20 days my most recent conversations were "I need some info from your server - can I call you back Friday for that?" (Adobe tech support) and "I have a possible fix - do you mind if I try it on our SharePoint system and get back to you?" (Microsoft)
Simply put, with 11.0.0 you CAN open .pdf files in SharePoint and with 11.0.3 you can't. Tested in Reader and Pro on multiple computers. We can open .pdf files on local computers and it is my firm opinion that this has nothing to do with Internet Explorer, SharePoint or how we install any of the above. The problem is in Adobe 11.0.3 (and other versions apparently) but tech support needed an hour to verify just that what I was saying was true (through remote access.) I could be wrong of course, but I'd appreciate ANY help anyone can give me since holding at 11.0.0 (which does work) opens us to hacker attempts according to the 11.0.3 update (which doesn't work.) Thanks!