What you'll need:
Your computer, a friend's computer.
Adobe CS5 shares its PDF setting across the applications, so they're read from one hidden folder in the C:.
Download and install trial version of InDesign from the Adobe website onto your friend's computer.
On BOTH computers, go to Control Panel, Folder Options and click the tab Show, scroll down a little and click Show hidden files and folders.
There should now be a folder showing called ProgramData, navigate to C:/ProgramData/Adobe/ on your computer. There should be a folder here called Adobe PDF, this is where the presets are stored. If it is not here, then we need to copy from your friend's computer.
Once the installation on your friend's computer is done, navigate to the same place and copy the Adobe PDF folder onto a USB stick and paste it into C:/ProgramData/Adobe/ on your computer.
Fire up your Adobe program and see that your PDF presets are there :)
Hope this helps some people, I spent three days trying to fix this and Adobe themselves were NO help!