I have this weird error that I haven't come across before. I have recently upgraded to 05.01.01 and Announcements 4.0.3 and recently started noticing this error. When I am logged in as the host user I have no issues as I believe the host user has en-US set as the default language. The issue appears when a user logs in that I have setup to use en-AU as their default language.

I can sort of replicate the issue as the host user by chaning the url:
 From: http://mysite.com.au/Wiki/tabid/253/language/en-US/Default.aspx (No Error)
 To: http://mysite.com.au/Wiki/tabid/253/language/en-AU/Default.aspx (Causes Page Load and Module Load Error)

Here is the error from the Event Viewer:

ModuleId: 516
ModuleDefId: 113
FriendlyName: Company Events
ModuleControlSource: DesktopModules/Events/Events.ascx
AssemblyVersion: 5.1.1
PortalID: 3
PortalName: Intranet
UserID: 1
UserName: host
ActiveTabID: 253
ActiveTabName: Wiki
RawURL: /Wiki/tabid/253/language/en-AU/Default.aspx
AbsoluteURL: /Default.aspx
AbsoluteURLReferrer:
UserAgent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; GTB5; InfoPath.2; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; MS-RTC LM 8)
DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
ExceptionGUID: 8f7ff37c-3775-4f93-a350-cd6682049090
InnerException: Conversion from string "9/25/2009" to type 'Date' is not valid.
FileName:
FileLineNumber: 0
FileColumnNumber: 0
Method: Microsoft.VisualBasic.CompilerServices.Conversions.ToDate
StackTrace:
Message: DotNetNuke.Services.Exceptions.ModuleLoadException: Conversion from string "9/25/2009" to type 'Date' is not valid. ---> System.InvalidCastException: Conversion from string "9/25/2009" to type 'Date' is not valid.at Microsoft.VisualBasic.CompilerServices.Conversions.ToDate(String Value)at DotNetNuke.Modules.Events.EventBase.get_SelectedDate()at DotNetNuke.Modules.Events.EventMonth.Page_Load(Object sender, EventArgs e)--- End of inner exception stack trace ---
Source:
Server Name: WIN2K3STD