Dear Sebastian, I have another problem also for same site. My SQL is growing very Fast and now it's Very Huge capacity. Look:

The 'savrina.ae' subscription, owned by user 'Ahmad Yaghoubi', is approaching or already exceeded the resource usage limits:

Disk space: 10 GB limit / 12340.5 MB (121%) used / 0 MB (0%) remaining
Microsoft SQL database quota: 512 MB limit / 6037.6 MB (1179%) used / 0 MB (0%) remaining

It is wonderful! I Use following Query but nothing happen :(

use [savrina_ae_]
truncate table sitelog
truncate table eventlog
truncate table schedulehistory

Also Files are less than 700MB but in Parallel Plesk 12.08 Like that Message come to me every day.....

Is it Plesk Mistake and bug? or DNN?

Yes, Exactly.... My GOD....
It's thousands of fake user registrations... but I could not seen in User Account List! my user account list is only 3 Users but in dbo.aspnet_Membership they are thousands ... my God///

How can Delete them? Because I Never let Register for this site and I put "None" in site settings....!!!! WOW... There is big problem in DNN Registration system I think. I don't know...
I have 8 Websites like this....

I execute following query but it just deleted 30 users from 13785 fake users. I think these users was on old Sub-Portal as I could not delete it before as I told you before:

UPDATE savrina_ae_.dbo.UserPortals SET isDeleted = 1
WHERE UserID NOT IN (SELECT UserID FROM savrina_ae_.dbo.Users WHERE isSuperuser = 1 OR UserName Like 'Admin')

Now, I have 3 portals in on DNN: "0" and "4" and "5"

I could not Delete Portal "0" because that error:

Error: Site Management is currently unavailable. DotNetNuke.Services.Exceptions.ModuleLoadException: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. ---> System.Data.SqlClient.SqlException: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. ---> System.ComponentModel.Win32Exception: The wait operation timed out --- End of inner exception stack trace --- at System.Data.SqlClient.SqlInternalConnection. (SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction) at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose) at System.Data.SqlClient.TdsParserStateObject.ReadSniError(TdsParserStateObject stateObj, UInt32 error) at System.Data.SqlClient.TdsParserStateObject.ReadSniSyncOverAsync() at System.Data.SqlClient.TdsParserStateObject.TryReadNetworkPacket() at System.Data.SqlClient.TdsParserStateObject.TryPrepareBuffer() at System.Data.SqlClient.TdsParserStateObject.TryReadByte(Byte& value) at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady) at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString) at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async, Int32 timeout, Task& task, Boolean asyncWrite, SqlDataReader ds) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, TaskCompletionSource`1 completion, Int32 timeout, Task& task, Boolean asyncWrite) at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, String methodName, Boolean sendToPipe, Int32 timeout, Boolean asyncWrite) at System.Data.SqlClient.SqlCommand.ExecuteNonQuery() at PetaPoco.Database.Execute(String sql, Object[] args) at DotNetNuke.Data.PetaPoco.PetaPocoHelper.ExecuteNonQuery(String connectionString, CommandType type, Int32 timeout, String sql, Object[] args) at DotNetNuke.Data.SqlDataProvider.ExecuteNonQuery(String procedureName, Object[] commandParameters) at DotNetNuke.Data.DataProvider.DeletePortalInfo(Int32 PortalId) at DotNetNuke.Entities.Portals.PortalController.DeletePortalInternal(Int32 portalId) at DotNetNuke.Entities.Portals.PortalController.DeletePortal(PortalInfo portal, String serverPath) at DotNetNuke.Modules.Admin.Portals.Portals.OnGridDeleteCommand(Object source, GridCommandEventArgs e) --- End of inner exception stack trace ---

How can Delete this Portal and how can delete about 14,000 Users? I saw these list on dbo.Membership also on dbo.UserPortal and dbo.Users.... I don't know how can finish this Story...
I have 8 Other Websites with same problem only for Spam Registration. My GOD.... Please help....