Medium Trust and Impersonate

Running system.io in a medium trust will require you to setup your web.config with impersonate.

This will be your main Plesk Login or Windows with your original password (some times current password).

<?xml version="1.0"?>
<configuration>
<appSettings/>
<connectionStrings/>
<system.web>
<identity impersonate="true" userName="servername\myUserName" password="myPassword"/>
</system.web>
</configuration>