Email of lost password, email from users account, Admin email blast all work fine. Notification Emails for PMs to or from any user do not. I find this error in the error log for every test PM. Any Advice?

System.InvalidCastException: Specified cast is not valid.

at System.Data.DataRowExtensions.UnboxT`1.NullableField[TElem](Object value)

at System.Data.DataRowExtensions.Field[T](DataRow row, String columnName)

at YAF.Classes.Data.TypedUserList..ctor(DataRow row)

at YAF.Classes.Data.DB.b__15(DataRow x)

at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()

at System.Linq.Enumerable.Any[TSource](IEnumerable`1 source)

at YAF.Classes.Core.YafSendNotification.ToPrivateMessageRecipient(Int32 toUserId, String subject)

1.9.5RC is outdated version. Current release is v1.9.5.5 RTW (available on CodePlex and here on the forums). Those issues should be resolved in this version. It is recommended you upgrade your installation.