Found this-
2. How can I prevent the U3 Launchpad from running automatically?
To turn off the U3 Launchpad autorun click on Settings and then select U3 Launchpad Settings. In the U3 Launchpad Settings window click on the Autorun tab on the left and then click the Disable Autorun button.
If the U3 Launchpad version on your U3 smart drive does not support this feature you can upgrade to the latest version of the U3 Launchpad. Click here to learn how to check for updates to the U3 Launchpad.
If you do not want to upgrade the U3 Launchpad or the flash drive manufacturer does not provide an upgrade for your drive yet, you can use one of the following methods to disable the U3 Launchpad from autoruning:
1) Hold down the shift key while inserting the smart drive. Keep holding the shift key until Windows plays the sound which indicates that a USB device has started. Now you can use the U3 smart drive as a normal USB mass storage device. To start the Launchpad after suppressing it, open MY Computer and double-click LaunchU3.exe from your U3 smart drive.
2) To permanently disable the U3 Launchpad from autorunning you must edit the registry of your PC. Please refer to this Microsoft Knowledge Base article for instructions: KBID 155217. Please note that this will disable other programs to autorun from a CD-ROM (e.g. Installation programs that automatically run when you insert a CD-ROM in your computer).
from here-
http://u3.com/support/default.aspx#CQ3