I'm just guessing here, but what the heck. I notice that templates_c is longer than 8 characters. Could that be any part of the problem?
In general, the template_c problems are permission problems. Could Apache and IIS be using different permissions for the directory? Perhaps Apache is running as one user (with permissions) and IIS is running as a different user (without permissions)? Have you changed the templates_c directory to be writeable for everyone?
I think you'll need to look in your error logs. Blank screens are often server errors. There are two logs to check: the server error log and the PHP error log. I'm not familiar with IIS, so you'll have to ask someone else where to look for those logs. One of them will report an error that will tell you what the problem is.