1. Show me your project! YoYo have given me 10 copies of the $100 Professional edition to give to my favourites. E-mail a link to a YouTube video of it to pentadact+noxp@gmail.com by 23-05-2015. You can see what's different in the Pro edition here: https://www.yoyogames.com/studio
3. We're using the free 'Standard' edition of Game Maker Studio 1.4 for Windows, which you can grab here: http://www.yoyogames.com/studio/download
If the version you're using has resource limits, it's not the same one.
4. If you're trying to follow this and it's not working, download the source code for this part from here: https://www.dropbox.com/sh/368nuqqpg9lz1su/AADYdbXud4XM62v1Df1bb7Fta?dl=0
And open it in Game Maker. If it works, your code must be different somewhere, so look for that. If it doesn't work, it's either something to do with Game Maker or differences in our computers.