Wordpress errors on windows IIS hostiing?

Question

I have installed latest wordpress version on my WINDOWS 2003/IIS server, which has PHP support enabled. All goes well except few things:

1. When I am trying to update a plugin automatically from wordpress dashboard, then it gives me this error "Could not remove the old plugin. Plugin upgrade failed."

2. I tried to edit CSS of my theme, but when I am saving it, it gives this error "failed to open stream: Permission denied in D:\www\example\wp-admin\theme-editor.php on line 74"

Could anyone please help me to fix these issues. I have given all permissions ("Modify") on the root and its sub folders as well, still this gives me such error.

Please help.

Thanks