Dear Sir or Madam, I have recently bought the MathCad 12 Student Edition, but unfortunately it has neither worked on Windows XP nor on Windows Vista properly. First I have entered the Product-Key on both systems correctly and MathCad has been installed. On Windows Vista I have not been able to open mathcad.exe. To activate MathCad I have to open it, right? On Windows XP I have had the same problem besides opening mcad.exe for activation. After double-clicking on mathcad.exe and mcad.exe I have seen a running window, but it has been shut down. What is my fault? I'm looking forward to hearing from you and thank you in advance. Best regards, Philipp Tuchel