Same here, list view does not work with 4.5.5 and 3.3.8. COuld use the fix here as well.

Error: Calendar is currently unavailable.
DotNetNuke.Services.Exceptions.ModuleLoadException: Object reference not set to an instance of an object. ---> System.NullReferenceException: Object reference not set to an instance of an object. at DotNetNuke.Modules.Events.SelectCategory.get_SelectedCategory() at DotNetNuke.Modules.Events.EventList.BindDataGrid() at DotNetNuke.Modules.Events.EventList.Page_Load(Object sender, EventArgs e) --- End of inner exception stack trace ---

Event viewer is full of these

ModuleId: 4506
ModuleDefId: 95
FriendlyName: Calendar
ModuleControlSource: DesktopModules/Events/Events.ascx
AssemblyVersion: 04.05.05
PortalID: 0
PortalName: PortalName
UserID: 458
UserName: -1
ActiveTabID: 599
ActiveTabName: Calendar
RawURL: /Home/Calendar/tabid/599/Default.aspx
AbsoluteURL: /Default.aspx
AbsoluteURLReferrer: http://myurl/Events/tabid/69/Default.aspx
UserAgent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; .NET CLR 3.0.04506)
DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
ExceptionGUID: 5a7defb4-6444-4b4e-842c-a5b042abb298
InnerException: Object reference not set to an instance of an object.
FileName:
FileLineNumber: 0
FileColumnNumber: 0
Method: DotNetNuke.Modules.Events.SelectCategory.get_SelectedCategory
StackTrace:
Message: DotNetNuke.Services.Exceptions.ModuleLoadException: Object reference not set to an instance of an object. ---> System.NullReferenceException: Object reference not set to an instance of an object. at DotNetNuke.Modules.Events.SelectCategory.get_SelectedCategory() at DotNetNuke.Modules.Events.EventList.BindDataGrid() at DotNetNuke.Modules.Events.EventList.Page_Load(Object sender, EventArgs e) --- End of inner exception stack trace ---

Thank you so much for posting this workaround.  It is a lifesaver for my site.  I currently do not use categories so disabling them has no impact.  My users really liked the list of upcoming events.

We actually recompiled the dll w/the code below

Public Property SelectedCategory() As String
            Get
                If _SelectedCategory Is Nothing Then
                    Dim objCookie As HttpCookie = Request.Cookies("DNNEvents")
                    If objCookie Is Nothing Then
                        _SelectedCategory = ""
                    Else
                        Me.SelectedCategory = objCookie.Values("Cat" & ModuleId.ToString)
                    End If
                End If
                Return _SelectedCategory
            End Get
            Set(ByVal Value As String)
                Try
                    _SelectedCategory = Value
                    Dim objCookie As HttpCookie = Request.Cookies("DNNEvents")
                    If objCookie Is Nothing Then objCookie = New HttpCookie("DNNEvents")
                    objCookie.Values("Cat" & ModuleId.ToString) = _SelectedCategory
                    Response.Cookies.Add(objCookie)
                Catch ex As Exception
                End Try
            End Set
        End Property

But oddly enough, it caused problems with month and week view, though list view is fine. I'm going to look at it closer, 
but I did end up rolling back to previous version for now.