Titan simulator stops working

[henkw]

I am using the Titan Simulator (8.1). I installed it in december 2014 and everyting was fine. I haven´t used it for a while, and when I start the simulator now, after I click on one of the five consolles, nothing happens. The simulator keeps running on the backgrond (says Windows Task Manager) but no new window with a virtual console pops up, nor does it show in the Task Manager... Also, when I open Titan One or Titan Mobile, no new screen appears, but WTM says the program is running.
How can I fix this?

Windows 7 64 bit
8 GB RAM
ATI Radeon 7900 series
2 screens

I had the same configuration when things where running fine in december. I tried re-installing and even installing a lower version (7.5 or 8.0) but nothing worked.