Took me less than 24 hours of owning Windows 7 Home Premium before I figured out a way to crash it.

This is a hard lock and requires power off to restore.

What you need:

2 x external usb disks

1 x very large file (I used a dvd iso file for testing) located on your desktop

Insert the two usb disks.  It doesn't matter which goes where or what drive letter they are assigned, however, you need to know what drive letters are assigned to them (My Computer)

Open up Control Panel - Administrative Tools - Computer Management

Browse to Storage - Disk Management

Start to copy the large file to either of the USB disks.

Before the file copy completes, change the drive letter of the 2nd usb disk to any unused drive letter (make sure you change the drive letter of the disk not being copied too)

The file copy will come to a screeching halt, even though it is being copied to the usb drive that didnt have the drive letter changed.

Within about 20 minutes, explorer will stop responding.

CTRL + SHIFT + ESC to open task manager

Attempt to kill running processes, even attempt to kill explorer.....

The system is hard locked and totally unresponsive.  CPU Usage will be near 0%  On my system, memory was at about 2.6GB out of 8GB.

Eventually even the start menu stopped working.  Only recourse was to power cycle the system.

On reboot, I was able to duplicate this repeatedly.

So, I bought this new logitech wireless keyboard and mouse from walmarts.  I get home and my dual computer / single monitor display through a kvm switch wouldn't work because the keyboard doesn't have a scroll lock key (which you press twice to activate the kvm switch to switch to another computer).  I use Linux, so the fix was really easy.

First, some details:  The combo package is labeled as Logitech Cordless Desktop LX310 Laser.  It includes a Y-RAZ71 keyboard and a mouse with a tilt-wheel (unknown part number).

The keyboard does not have a scroll lock key.  However, moving the tilt-wheel twice to the left or right activates scroll lock and switches the kvm switch.  This method works in both windows and linux computers without any other settings.  On windows, if you click start-run and type osk for on-screen keyboard and move the tilt-wheel, you will see it does in fact highlight the scroll lock key on the keyboard.