Blender Doesn't Start

[nexusguy]

So i have 2 versions of blender, one for modelling and one for exporting, they are 2.78 and 2.49b respectively. On the first time i installed blender 2.49b i followed the exact instructions and it didn't work, then ,for some weird reason, it started to work properly, however i recently opened it to import a nif and it crashed on start, the weird thing is that i can see the blender interface for a split second before it crashes. So i reinstalled everything as instructed and it didn't work again, i tried setting a specific enviromental variable for it, but to no sucess , alas my blender 2.78 stopped working after i inserted that variable, so i deleted it and it worked again(phew...). So my question is , is it a incompability between older blender versions and windows 10 or version mixing problem? Because i installed on my notebook, which has win 7 and it worked flawlessly, but i can't seem to make it work on my computer. However i do have 2 versions of python installed, one is for the latest blender build, which is python 3.6.1 and the other for the older one, python 2.6.6, is blender 2.49b not recognizing the correct python version it is supposed to use? So how do i proceed in this case, how do i fix it, if it is fixable, pls can someone help me?