SQL Server 2008 R2 .mdfs write protected I had to replace my hard drive, XP pro sp3, and all my applications - including SQL Server 2008 R2 developer edition. My databases are all on a separate physical drive. I find I cannot move or copy them to a different folder, I cannot flip the read-only flag, and I cannot attach them to the database server.

I am logged in as administrator and accessing management studio as sa.  None of the other user files are write protected on that drive.
Might be OS-level access rights--every now and then I hit something like this. In Windows Explorer, right click on the file and select properties. Go to the Security tab. Are there any entries in the "Group or usernames:" box? These are the entities that can manipulate the file. Yes, even if you are local and domain admin, you can be blocked from accessing a file.

However, you can't be blocked from managing access rights over the file. Click on "Add...", grant yourself (or whoever) "Full Control", and you should be good. (If, of course, this is the actual problem.)