SQL Server reporting services scheduler loops, running amok

We have a Windows Server 2008 R2, Service Pack 1 with an SQL Server 2008 R2 (Microsoft SQL Server Standard Edition (64-bit), version 10.50.4042.0) for creating scheduled reports in SSRS. The Report Server services didn't start up after a server restart a while ago and when I noticed that after several days, I started the service. Then it began to loop thru all reports constantly, as if the server not was aware of that it had already done that report.

When I look in the table [ReportServer].[dbo].[ExecutionLogStorage] I can see that new reports are created constantly as fast as the previous report is ready. It looks to loop thru all reports.

I found two errors in Windows application log which maybe are connected to the problem, or not.

Failed to unload app domain DefaultDomain. The following exception occurred: Error while unloading appdomain. (Exception from HRESULT: 0x80131015).

ProcessName: ReportingServicesService ProcessId: 4308 Failed to trace event: System.AppDomainUnloadedException: Attempted to access an unloaded AppDomain.

I really don't understand what to do. The server has been running for several years, doing the scheduled jobs without any problem. I have restarted SQL Server Agent, Reporting Services as well as the whole server and it doesn't make any difference.

I am thankful for any help.

Lage

I got help from MS Developer Network, so want to share it here if someone get similar problems.

https://social.msdn.microsoft.com/Forums/en-US/1cd9f753-02b2-4dea-a77a-0fa33fe80c7a/sql-server-reporting-services-scheduler-in-infinite-loop-spamming-reports?forum=sqlreportingservices

Best regards

Lage