I've tried to delete dialogue members from two different websites to see if the issue either lay with my code or something in Dialogue. When I do try to delete, I'm told to refer to the log file which tells me the followings:

 2015-01-19 09:21:19,090 [5] ERROR System.Web.IHtmlString - [Thread 15] Dialogue Package: Error trying to delete Dialogue member
System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.
   at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
   at System.Collections.ObjectModel.KeyedCollection`2.get_Item(TKey key)
   at Dialogue.Logic.Services.MemberService.RefreshMemberPosts(Member member, Int32 amount)
   at Dialogue.Logic.Services.PostService.SyncMembersPostCount(List`1 members)
   at Dialogue.Logic.Services.PostService.Delete(Post post)
   at Dialogue.Logic.Services.MemberService.DeleteAllAssociatedMemberInfo(Int32 userId, UnitOfWork unitOfWork)

2015-01-19 09:21:19,095 [5] ERROR System.Web.IHtmlString - [Thread 24] Dialogue Package: Error trying to delete Dialogue member
System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.
   at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
   at System.Collections.ObjectModel.KeyedCollection`2.get_Item(TKey key)
   at Dialogue.Logic.Services.MemberService.RefreshMemberPosts(Member member, Int32 amount)
   at Dialogue.Logic.Services.PostService.SyncMembersPostCount(List`1 members)
   at Dialogue.Logic.Services.PostService.Delete(Post post)
   at Dialogue.Logic.Services.MemberService.DeleteAllAssociatedMemberInfo(Int32 userId, UnitOfWork unitOfWork)


2015-01-19 09:21:19,110 [5] WARN  System.Web.IHtmlString - [Thread 15] Dialogue Package: There was an error attemping to delete member barry scott and all of their associated data (Posts, Topics etc...)
2015-01-19 09:21:19,131 [5] WARN  System.Web.IHtmlString - [Thread 24] Dialogue Package: There was an error attemping to delete member bryanredban and all of their associated data (Posts, Topics etc...)
2015-01-19 09:22:07,960 [5] ERROR Umbraco.Web.Scheduling.ScheduledPublishing - [Thread 8] An error occurred with the scheduled publishing
System.Net.WebException: The remote server returned an error: (404) Not Found.
   at System.Net.WebClient.UploadDataInternal(Uri address, String method, Byte[] data, WebRequest& request)
   at System.Net.WebClient.UploadString(Uri address, String method, String data)
   at Umbraco.Web.Scheduling.ScheduledPublishing.Run()

I've tried completely uninstalling dialogue. Manually deleting everything (including the databases). Re installing over the top in case the first install missed something, but the issue still resides.

Has this happened to anyone else?

I installed dialogue from inside Umbraco itself. I can do everything else i need to, I just can't delete any members.