You don't tell whitch version of Windows you use :(
Anyway, with all version of Windows tou can use Ctrl+Shift+Esc to start the task manager. Find the offending process. Take note of it's name. Kill it.
If you kill the problem process, the white screen will go away.
If you still can's get the task manager, or are denied killing the process, try this:
Try starting in safe mode.
Try holding the Ctrl key while the desktop is loading (do it when the welcome screen appear or just after sellecting a profile) It prevent most startup items from starting.
You can also use Atl+F4 to close the application that have the focus.
You can use the Window key+D (show desktop shortcut) to minimise all windows.
Window key+M is the minimise all shortcut. Window+Shift+M to restore.
Check your startup processes. You may find them in those locations:
Start menu/All programms/startup
In the registry (Window+R, type "regedit" + enter):
navigate to:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\run\
Suppress the entry that looks like the problem task.
Go down one line to the \RunOnce\ entry
You can delete anything here except the (default) entry. It's value must be "Not set". Clear it if it contains anything.
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\run\
and \RunOnce\
Do the same. Be sure you don't touch the entry for your anti-virus.
Electro, February 2013
