Dell Vostros Touchpad Drag Feature

The Touchpad on my 5620 will no longer allow me to use the drag feature for anything. Everything else on the touchpad works fine. The problem is that I cannot resize windows, select partial text, or anything that requires the drag feature. In the Touchpad settings, the Touchpad is set to "ON". In the Tap settings, all four features are selected. Everything works fine if I use an external mouse. The Touchpad diagnostic shows it to be working correctly. I have uninstalled and reinstalled the driver numerous times (and rebooted). Has  anyone  experienced this or  know the  solution?