Could not write to output file -- Access is denied

My money is on your files are read-only. Verify they are read-only and change them or add your files to a source control system and let them get handled by that.

I think Karl has it right. I had a similar situation once, and what I did was delete the file in question, clean the solution, and then rebuild. If the project needs that file it should recreate it; in my case it didn't need it because it never recreated it, but the project ran just fine.

One other thing I would recommend; you may be selecting the read-only attribute of the parent folder off and selecting this setting to recurse through all sub-folders and files, but that doesn't mean that's what's happening. For all your sub-folders and files (especially the ones that are cropping up as errors) inspect each one individually and make sure the read-only attribute is off.

it seems that the same error is sometimes displayed when the app pool user doesn't have access to the %TMP%/%TEMP% folder.

You'll need to grant IIS_IUSRS read and modify access over the temp folder of the user the app pool is running as.

This could either be the temp folder in the app pool user's profile, e.g. c:\Windows\ServiceProfiles\NetworkService\AppData\Local\Temp, or the system temp folder at c:\windows\temp.

I was able to get this working by closing Visual Studio and then opening it again, but being careful to run Visual Studio "As Administrator". To do this, from the Start menu, right click on Visual Studio and choose "Run as Administrator".