We have a customer who does their own development with umbraco and basicly just help on the side and host a bit for them.

Ive just got handed a project of theirs that they done through webmatrix, so I scaled up the base easy peasy. 

The frontend works but whenever we login to the backend we get an error. 

"index was out of range bla bla bla".

Here is what gets thrown from the umbraco log : 

At /umbraco/umbraco.aspx (Referred by: http://furflow.dk/umbraco/login.aspx?redir=/umbraco/umbraco.aspx): System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.  Parameter name: index     at System.Collections.Generic.List`1.get_Item(Int32 index)     at umbraco.cms.presentation._umbraco.Page_Load(Object sender, EventArgs e)     at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e)     at umbraco.BasePages.BasePage.OnLoad(EventArgs e)     at System.Web.UI.Control.LoadRecursive()     at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

 We get logged in and forwarded to /umbraco/ but here it throws the error. I know the project is filled with all the sql CE dlls/settings and such. Could this be the cause ?