Case solved. Speed Commander is the culprit. That's why zooming did work only occasionally. Whenever I start up PSPad from outside Speed Commander, everything works fine.
It is still puzzling, though. I have been using Speed Commander for years, I launch all my applications from there, never experienced any problems. Will do some further testing with multi-user options, installed versus portable scenarios, etc. -- <http://forum.pspad.com/read.php?2,57681,57778> PSPad freeware editor http://www.pspad.com
