Built in trackpad not responding correctly - Dell Inspiron

Hello again Seveners!

I come to you with yet MORE computer problems! Hopefully you brainboxes can find out what's up this time, too!

Okay - so my friend has asked me to try and fix his Dell Inspiron N5040. I have tried, but to no avail, and am seeking 7-support!

The built in trackpad is playing silly buggers. When the computer has logged in (and Windows in finalising the loading of programs), left clicking with the mouse causes the right click menu to open. This is rather annoying. After about 5 minutes, the problem goes away and is fine.... for about 5 minutes! It then keeps trying to right click everything, makes me unable to click on the Start button or any other Taskbar items for that matter. The only way to make it work again is by pressing Ctrl + Alt + Delete and then pressing escape. It will then happily allow me to left click again - as if by magic!

The same thing happens if I try and use an external USB mouse, although it is a lot more reliable than the built in trackpad.

I do have a technical brain, so I have thought and tried the following. Hopefully you can see something I overlooked!

- Checked that the trackpad wasn't disabled - but no - the trackpad still allows me to move, just clicking with the buttons wont work. I will also add that it stops be being able to click using the touchpad rather than the buttons, too.

- Uninstalled and reinstalled the drivers. - Same problem.

- Tried to update the drivers - Marked as up to date.

- Checked the mouse settings to ensure that the buttons are not marked as swapped. - They're not.

- Restarted the PC - many, many, many times!

- Checked no settings were changed on the BIOS - there isn't anything to do with the mouse on the BIOS!

- Done /sfc scannow to see if there were any issues with the OS - there was not.

- Checked for Windows Updates - Everything (including optional updates) is updated.

- Checked the properties of the mouse to see if there's an error code - there's none.

I am not thinking hardware problem, as I can easily solve it by CTRL+ALT+DEL'ing. I am really stuck! Help?

Cheers!

If I had to make totally wild guess, I would speculate there is another program running that takes control of the pad. I would boot in a safe mode to see if that helps, if not I would try to look at all services running and disable some. Usually there is brief description to give you an idea if it's safe to disable. I don't see virus scan in your list, I would start with that.