I just converted from Dreamweaver MX to CS5. I access my files that were made in MX (held on an external hard drive) using CS5. I cannot save changes to website pages using CS5. When I try to view in IExplore, and I am prompted to save, I get a message giving me the path where the file is at and a message starting with access to... and ending with "was denied". Nothing more is provided to me.
First thing that springs to mind is are you developing dynamic PHP, CF or ASP pages? If so, have you got a web server set up on your new computer such as apache or IIS?
If you have, the only way I am able to serve dynamic pages is to have the pages in the actual web server htdocs or wwwroot folder. If you were able to serve pages from an external hard disk, then I assume you had some sort of setup that enabled you to get those pages working outside of the htdocs or wwwroot folder which I am not aware of.
My only other suggestion is that you might have a folder permission that is only allowing admin access, so you might need to look at and change the permissions which you'll find in the properties or get info of the folder.