This is usually a symptom of either the basic driver being installed (not the OneTouch 4 software), the destinations for the buttons not being set in the OneTouch 4 software correctly or the monitoring program not being active. (For the X7600, the OneTouch 4 software comes with PaperPort programmed as the default destination for the scan button. If that setting got changed, it could cause the problem.)
The drivers and software are available here: http://www.xeroxscanners.com/en/us/products/drivers.asp?PN=X7600
. Scroll down for the manuals. If you have the basic Xerox driver installed, uninstall it (remove the scanner from the Device list by right clicking on it and choosing uninstall) then disconnect the data cable. Finally restart the computer and then install the One Touch 4 software.
If you have the OneTouch 4 software installed, check if the program is set to run on startup.
Click Start > Run then type "msconfig" (without the quotes) in the Open box. Click OK. Choose the startup tab and look for the Xerox software. Make sure the box is checked. Click Apply after changing the settings and restart the computer.
Next, launch the program (Start > All Programs) and try to launch a scan from the One Touch
button panel on the computer. Adjust the settings if needed in the
Configuration section of the software (see the manual for screen shots).
I hope this helps.