We are having, I believe, all of the same issues listed in this very long thread. Our Acrobat Pro X users get this error message "The URL you have provided could not be reached. Pease verify that the URL is correct and that the network location is reachable" when trying to open a pdf froom Sharepoint 2010. They can see the most recent version with no problem but they (and not ALL) get this error message when trying to view a previous version. It cannot be a permissions issue as they all have the same permissions. Not sure if you need any additional info, but any information you could share on how to fix this issue would be greatly appreciated.
Been searching for 2 days for a solution.