I downloaded Python 3.0.1 and installed on Vista. I opened IDLE and it 
worked fine. I went into the Preferences to change the keybindings on 
the history scrollers. I changed history-next to Ctrl+Down Arrow, 
though when I pressed OK it listed only Control as the binding. I then 
tried to change history-prev to Ctrl+Up Arrow, but when I pressed OK, 
it gave an error that that binding was already taken. The program then 
crashed. Since then whenever I try to open IDLE, the pythonw.exe 
process appears in my Task Manager briefly, but then it exits, and I 
never see any other evidence the program has opened. The command line 
still works fine. I tried repairing the installation, uninstalling, 
restarting the computer, and removing the leftover registry keys for a 
completely clean install, but nothing has worked to be able to reopen 
the program.