** WINDOWS XP **
When a patch becomes unstable, for example because of an infinite loop or almost such, and you "kill" it with window's Task Manager (in the Applications panel), AFTER it is supposed to have been closed (and windows has already sent the error report to Bill Gate's personal trash can),
sometimes the pd.exe process keeps running, without any window nor icon, and consuming a lot of cpu (since it keeps running the unstable patch).
In the Task Manager, "processes" panel, you then can find and kill it.
I often noticed that in windows PD has 2 main processes: pd.exe and one called "Wish84" or something like that, that I guess is the one with the main window and text output. I suppose the problem may be that when killing PD (I mean killing the PD application from the Applications panel of the task manager, NOT killing just the wish84 process from the processes panel), only the wish84 process is really killed - probably this only happens when the pd process is unstable.