I don't know if anyone has experienced this before
One minute you are happily compiling away fixing bugs in your .NET project and the next minue when you try to run your web application you get a permission denied error. The thing is the usual IISResets don't seem to solve the issue only a reboot does, how odd?
Investigate further and look into the Temprary ASP.NET folder and you'll find your application in there, try to delete it and even if you are an administrator on your machine you will get an access denied error as below.
Well it looks as though this little gem of an error is caused by MS Indexing Server trying to access the DLL at the same time your web app is and some how deadlocking. After a while it releases this lock, however a good way to stop it from happening is to either turn of Indexing Server or exclude the Temporary ASP.NET folder from Indexing Server.