Here's what I did to fix this. Start OpenOffice Writer then goto Tools --> Customize. Select the Keyboard tab from the Customize window that popped up (Pictured below). Select Edit in the bottom left list. Then select "Paste Unformatted Text" from the bottom right list and finally assign the keyboard shortcut you want it to be from the top list.
I notice that the F4 key (Function Key F4) is unassigned so I used it and went from a 4 key combo to 1.