Sounds like Windows, or your Touchpad's driver/utility has been set to "disable while typing".
To check/adjust the (generic) Mouse settings in Windows 8:
- In Metro Start, Click on Control Panel tile.
- Now click on More Settings option from left side menu.
- Old Control Panel Window will open. In Old Control Panel Window search for Mouse settings and click on Change Mouse Settings option from the search results.
- Mouse Properties window will pop up.
- Make adjustments as you'd like.
More info here: 4 Ways To Quickly Disable The Touchpad in Windows 8
If you installed an Acer or another 3rd party driver, and they have not just added/replaced tabs and options on that screen, then you may have to check with them for specific instruction.