Snap!  I am also getting this problem - I have been having a lot of issues with localization since upgrading to DNN 5 - I do not understand the language settings now and am unclear if I am doing everything right.

I have posted on the CATALooK forums but have not had a response.

Any help gratefully received.

Examples below! - Is it because I am not using the dotnet 3.5 framework?

UserAgent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; GTB6; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)
DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
ExceptionGUID: 19fddf8d-55b9-48ff-9875-37952f570084
InnerException: Object reference not set to an instance of an object.
FileName:
FileLineNumber: 0
FileColumnNumber: 0
Method: CATALooK.C_Address.Localize
StackTrace:
Message: DotNetNuke.Services.Exceptions.PageLoadException: Object reference not set to an instance of an object. ---> System.NullReferenceException: Object reference not set to an instance of an object.at CATALooK.C_Address.Localize()at CATALooK.C_Address.DataBindAddress()at CATALooK.ShoppingCart.InitPage(Int32 PageIndex)at CATALooK.ShoppingCart.DisplayCurrentPage()at CATALooK.ShoppingCart.Page_Load(Object sender, EventArgs e)at System.Web.UI.Control.OnLoad(EventArgs e)at System.Web.UI.Control.LoadRecursive()at System.Web.UI.Control.LoadRecursive()at System.Web.UI.Control.LoadRecursive()at System.Web.UI.Control.LoadRecursive()at System.Web.UI.Control.LoadRecursive()at System.Web.UI.Control.LoadRecursive()at System.Web.UI.Control.LoadRecursive()at System.Web.UI.Control.LoadRecursive()at System.Web.UI.Control.LoadRecursive()at System.Web.UI.Control.LoadRecursive()at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)--- End of inner exception stack trace ---
Source:

UserAgent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; Win64; x64; SV1; .NET CLR 2.0.50727)
DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
ExceptionGUID: f3ef1186-dd56-4214-ad3f-2fa6e53ba3b3
InnerException: The relative virtual path 'profileproperties_telephone.ascx.portal-0.resx' is not allowed here.
FileName:
FileLineNumber: 0
FileColumnNumber: 0
Method: System.Web.VirtualPath.FailIfRelativePath
StackTrace:
Message: System.ArgumentException: The relative virtual path 'profileproperties_telephone.ascx.portal-0.resx' is not allowed here.at System.Web.VirtualPath.FailIfRelativePath()at System.Web.Hosting.HostingEnvironment.MapPathActual(VirtualPath virtualPath, Boolean permitNull)at System.Web.Hosting.HostingEnvironment.MapPath(VirtualPath virtualPath)at DotNetNuke.Services.Localization.Localization.GetResourceFileCallBack(CacheItemArgs cacheItemArgs)at DotNetNuke.Common.Utilities.DataCache.GetCachedData[TObject](CacheItemArgs cacheItemArgs, CacheItemExpiredCallback cacheItemExpired)
Source:

I'm getting precisely the same problem with PayPalIPN.aspx here.  I believe the following path definition is the source of the problem:

~/DesktopModules/CATALooKStore/App_LocalResources/SharedResources.resx

I'm struggling to see what could be wrong with that.

Judging from the source of the catalook module their localisation code calls this:

DotNetNuke.Services.Localization.Localization.GetString

The variant with 2 string parameters, which is in my version of the DNN library project. The parameters being passed (assuming I have the correct bit of code, I think I have) are:

"PAYSTATE_0" and "

~/DesktopModules/CATALooKStore/App_LocalResources/SharedResources.resx"

Inspecting the resource file shows that it's both present and contains the data being searched for. This looks like it should still be supported to me. Sebastian, is there anything that looks like a problem to you? I have seen some localisation issues raised elsewhere as a bug, but that seemed to be to do with absolute paths not being supported.