Unity 4.6.2 Monodevelop Net framework issue

Hi, im starting to learn unity, i downloaded unity 4.6.2 a few days ago, i havent used it too much, but today i was starting a little project, and my problem is that when i create and try to open a script from the unity editor (with monodevelop), it shows me an error. Basicly, it says i need to have Net Framework v4.0 installed, wich i already do have, i even tried a full reinstall of Net Framework, but the error persist. Any toughts of what could be?. If i cant fix it, should i try using another IDE with unity? Thanks.