A few months ago I was having problems with Visual Studio 2008 when I was trying to compile:
I was getting "unrecoverable build error" and a .tmp file was giving me 'Access is Denied'. At first I thought it was because Microsoft Office was Breaking Visual Studio as I posted here. Then I did some research and according to Microsoft VS 2008 displays the "unrecoverable build error" when it can't determine the exact reason for failure. This meant it was probably related to the previous error.
When I would browse to C:\Users\name\AppData\Local\Temp and delete all the files, that still didn't help. Another coworker said they turned off our backup software (CrashPlan) and it worked! Somehow CrashPlan was constantly checking the same files that Visual Studio was trying to access and created a ownership conflict.
Now before I doing any compiling in VS 2008 I set my backup software to sleep. Problem fixed!