Opening a C# script to edit does not work

I was following the Roll-a-Ball tutorial and got to the part where you create the player movement input C# script. However whenever I try to open the script to edit it the Mono Developer opener flashes up twice and then does nothing. The console currently has an error but I do not know what it means due to this being my first time programming and using Unity. It reads: Build Target directory for does not exist!WebPlayer
It may be important to note that I am using the PSM version of Unity which could differ from the normal version in some way.

try uninstalling unity and then reinstalling it