We are struggling to fix our application that has been in the field for some time and in the last month started hanging from what seems to be a network printer issue. Intermittently, and more often on Vista that XP when a user changes the default network printer to another printer - network or PDF for example - the application will freeze. The window will not repaint and it appears to be a ghost image. Sometimes you can click the application button in the bottom bar and it will repaint but the complete interface is dead. The CPU usage is essentially nothing, the memory is about normal and the task manager says the app is running but you can not get any control to work and if you hit the button in the bottom bar it beeps as though there is an open error message dialog - but there isn't. All other applications on the machine operate normally. The only way to get the program to close is via task manager and kill it. We have numerous try catches within the app and we are unable to get any error message indicating where the error is from. A related issue it seems is that some of our users have Quick Books going at the same time and if they are printing a PDF and try to work with our app the same thing occurs. If they wait until Quick Books completes the PDF generation and then work with the app, all is well. This seems to be another case of the printer being involved. We have used Spy++ and we see the incoming system change message but 99% of the time nothing happens. We use printdocuments in a few places in our app but have checked all cases to be sure the printdocument is disposed when a printing occurs. We do not hold a reference print document at a global level for printing use. Can someone give us a clue what to try to figure this out. It is destroying our system since about 25% of our users have started having this disrupt their daily operations but we can not replicate it in any lab setup so we can debug. It seems to be in the framework itself since in no case can we find a section of our app code executing when it occurs. Thanks,
Terry Harrison