No rotation with middle mouse button

[3d_vitality]

Hi,

I had some problems with this befor 2.4, but after I installed 2.4 I can't longer use the middle mouse button (click & hold) to rotate the object around. Nothing happen no matter what I choose in preferences for the camera action.
Unfortunately this function is essential for me. Even with key combinations nothing worked....  surprisingly that behaviour is now the same also in my older wings installations (2.2.6.1, 2.2.9...)

Anyone any ideas / hints on this?

Thanks a lot in advance, Paul