Unfortunately this happens as a result of an incompatibility with some versions of Windows.
To correct, download this file:
http://media.naturalpoint.com/ftp/uploa ... 120705.zip
Extract it to your Program Files directory, then manually create a shortcut to TrackIR5.exe and install the drivers.
To install drivers:
Click on the start menu, then click on computer. On the ribbon at the top, select "System Properties"
On the left hand side of the window, select "Device Manager"
Look for a category called "NaturalPoint Devices". It should have an item inside called "TrackIR 5". If it does, double click on the TrackIR device and ensure that the window says "This device is working properly".
If there is no NaturalPoint Devices, look for an "Unknown device" with a yellow caution sign over the icon.
Right click on the unknown device, and select "Update driver software"
Click "Browse my computer for driver software"
Click "Browse" and point it to your "TrackIR5\Drivers" directory then hit next, and continue as normal.