nope, i am not aborting any thread. i forgot to add an important info: sharepoint is located on two servers, meaning there is a loadbalancing installed using two servers. could it be, the task is switched to the other server when returning? meaning when starting the printing from server A to sharepoint it looks like as if the server is very busy and when returning it is switched to server B, but there is not thread active so it thinks it is aborted? that's an idea which I had when talking to some other guys.