Error with Frequency Domain Solver in CST

My first post in a forum ever haha
I started using CST Microwave Studio by following the tutorials given with the documentation. Whenever I try to use the Frequency Domain Solver I get the following error message:
"An unsuccessful termination of the port mode solver has been detected. Do you want to start again with an alternative port mode solver?"
I read through most related parts of the help file, checked again if I have all the settings as told in the tutorials and tried to vary all possibly related (as far as I know) but it doesn't work with any of my models. To be true, I dont really know what is meant by the error message. The message window only says:" Terminated abnormally", which doesnt give much information as well.
In general the tutorials dont work just as described, for example I had to increase the mesh for the transient solver to run w/o errors. Took me a while to figure that out.
Thanks for answers!
Irenaius

can you post the tutorial and a screen print of the error ?

I did several turorials, I will give two examples:
1) CST MICROWAVE STUDIO - Workflow and Solver Overview
This tutorial is located in the CST Folder and part of the main documentation (simple T-piece waveguide)
2) The Antenna tutorial
This tutorial is located in the Help -> examples/CST MWS Examples/Tutorials/Antenna
Following the error message, which pops up first.