Can't delete source folder

I've added the Delete Files/Folders action to my build with the intention that if the build directory exists, it will be removed so that my build can be clean from source control (I don't want artifacts from the last build in my current build). Unfortunately I'm getting the following error in my build and I can't figure out how to get it to work correctly...

Deleting: *
An unhandled exception occurred while executing this action: System.IO.IOException: The directory is not empty. at Inedo.BuildMaster.Extensibility.Actions.RemoteCommandExecution.RemoteActionExecuterBase.remoteAction_RemoteCommand(Object sender, RemoteCommandEventArgs e) at Inedo.BuildMaster.Extensibility.Actions.RemoteActionBase.ExecuteRemoteCommand(String name, String[] args) at Inedo.BuildMaster.Extensibility.Actions.RemoteActionBase.ExecuteRemoteCommand(String name) at Inedo.BuildMaster.Extensibility.Actions.Files.DeleteFilesAction.Execute() at Inedo.BuildMaster.Extensibility.Actions.ActionBase.ParamlessExecute()

This is the first action that runs in my build and I have the following values in my action:

Source Directory: C:\Code\Build
Action is Enabled: True
Resume Next on Failure: False
Timeout: (default)
File/Directory Masks: *
Delete from all subdirectories: True
Log individual entries: False

Any help is appreciated.

It looks like for some reason one of the subdirectories beneath C:\Code\Build is not getting cleared. This could happen if there is either a file that cannot be deleted due to the directory's security attributes or a hidden file contained in one of the directories.

It may be helpful to enable the "Log individual entries" option to troubleshoot this problem - that way you should see which directory it gets stuck on.