In dnn 4.3 when you configure both of connection strings

like

<add name="SiteSqlServer" connectionString="Data Source=R2D2\SQLEXPRESS;Initial Catalog=dotnetnuke;Integrated Security=True" providerName="System.Data.SqlClient"/>

<add key="SiteSqlServer" value="Data Source=R2D2\SQLEXPRESS;Initial Catalog=dotnetnuke;Integrated Security=True"/>


in web.config file..but after installing dnn 4.3 successfuly when you run the application first time , dnn runs but shows some load exception.....

basically after installing it changes the paramter name in second connection string from "SiteSqlServer"  to "iteSqlServer"
...well guys i dont know it is really a bug or not..but it was happening with me consistently in my Windows XP....so makesure the parameter names are same in both of connection strings

turning off compression?...well to be very honest i have not come across of this word compression, when i was trying to install 4.3.....not even in installation guide... But dnn 4.0 had no problem with connection string before or after installing on my XP professional with service pack 2 unlike dnn 4.3