Open Internet Services Manager from the Administrative Tools group.Right-click on your server and select properties. From Master Properties choose WWW Services and click the “Edit…” button. Select the HomeDirectory, and under Application Settings click the “Configuration…” button.
In the list, you should see an item for ASP that looks like this:
asp C:WINNTSystem32inetsrvasp.dll GET,HEAD,POST,TRACE
You need to click the Add button and add a similar item for your .js, .vb, css files. Be sure to check the Script Engine checkbox for this to work.
js C:WINNTSystem32inetsrvasp.dll GET,HEAD,POST,TRACE
Also consider using the appropriate ContentType header for the type of file you are returning.