Every minute, another Scheduler Exception event is logged on my site.

Here is the logged event:

AbsoluteURL:

DefaultDataProvider:DotNetNuke.Data.SqlDataProvider, DotNetNuke

ExceptionGUID:46523844-dbcf-4a19-b5d3-e326834125d3

AssemblyVersion:

PortalId:-1

UserId:-1

TabId:-1

RawUrl:

Referrer:

UserAgent:

ExceptionHash:hfbNYAroBIONPgeWKaGxkw==

Message:Thread was being aborted.

StackTrace:

   at System.Threading.Thread.SleepInternal(Int32 millisecondsTimeout)
   at DotNetNuke.Services.Scheduling.Scheduler.CoreScheduler.Start()

InnerMessage:

InnerStackTrace:

Source:mscorlib

FileName:

FileLineNumber:0

FileColumnNumber:0

Method:

Server Name: WebA12

What causes this?