While it seemed like a great solution at first, the touchpad on your laptop is driving you crazy. It sticks when you need it and shoots the cursor to the side of the screen when you don't. Though you've purchased an external mouse, you haven't been able to shut off the touchpad, and it's still messing up your laptop navigation when you accidentally brush it. Though disabling the touch pad will vary depending upon your computer and software, it need not be difficult. Here are some ideas on how to get it off once and for all.
Check on your toolbar in the lower right corner. There may be an option for touchpad right there that will allow you to open touchpad settings. Double click, hit "Device Select" and select "Disable."
Go to "Control Panel" in the "Start" menu.
Select "Mouse" in the classic view of the control panel, or find it under "Hardware."
Select the "Touchpad."
Click "Device Select."
Select "Disable" and hit "OK" or "Apply." You could also check off the box that says "Disable touchpad/pointing stick when external USB mouse is present."