Hi kaushikreddy4,

Welcome to community. 

You may try to install the Touchpad driver in compatibility mode.

Steps to uninstall the Touchpad driver:

• Press and hold the Windows key and press 'R' key. This will open the run window.
• Type 'devmgmt.msc' without the parenthesis, click 'Ok'.
• Expand ‘Mice and other pointing devices’.
• From the list, look for ‘Dell Touchpad’.
• Right click, choose ‘Uninstall’.
• Check the ‘Delete the driver software for this device’, Click ‘Ok’.
• Restart the computer.

Steps to install the Touchpad driver:

• Click on the link: http://dell.to/1yZkjiE 
• Click ‘Download File’.
• Check on the radio box ‘Single-file download’.
• Click ‘Continue’.
• Click ‘Save’.
• Choose the location as desktop, save the file on the desktop.
• Right Click the driver installation file and select Properties -- > Compatibility Tab.
• Select Windows 7 from the list in the following image:

• Click Apply --> OK
• Right Click the file and select 'Run as Administrator' to install the driver.
• Restart the computer.

Steps to disable touchpad:

• Open Control Panel --> Mouse --> Dell Touchpad.
• Click ‘Device Select’.

• Check ‘Disable Touch pad/Pointing Stick when external USB mouse is present’

• Click ’Apply’ --> ‘Ok’.
• Restart the system.

 If the issue is not resolved then you will have to replace the palmrest. Below are details you can try. 

This is the part you'll need:

http://bit.ly/1nU6dq0 

And here are the replacement instructions:

http://bit.ly/1nU3i1M 

Please let me know for any further assistance.