Performing a search myself, I found a good action plan from lil-liebe.
http://h30434.www3.hp.com/t5/TouchSmart-PC/Touch-screen-not-working/td-p/759701
- Press the Windows logo key + X.
- Select Device Manager from the list.
- Click the little arrow next to Human Interface Devices to expand the list.
- Click the touch screen driver (in my case, NextWindow Voltron Touch Screen).
- Right-click, and select Enable from the list (if it is not already enabled).
- Click Yes on the dialog box that asks if you are sure you want to enable the touch screen driver.
If that does not work, you might try going to hp.com (http://www8.hp.com/us/en/support-drivers.html) and clicking Drivers & Downloads.
In the search field, enter your product name or number, and then click Go. Select your operating system from the drop-down list under Select your operating system, and then click Next. If there are any available graphics drivers under Select a download below, click the plus sign next to Driver - Graphics, and then click the driver name. In the Download options and information window, click Download . Follow the onscreen directions to download the driver. Restart the computer.