I've been running into this problem for a month now and can't find a work around. I already preformed the basic fixes of reinstalling java and minecraft, deleting the .tekkit folder, and made sure to run the launcher in admin as well. During update upon reaching the Modular Powersuits mod a small window with FML running will pop up, close, and then launch the main window to a white screen and then it will just stall like this for as long as 20 minutes without an error message appearing. I'm guessing whatever the problem is has to do with the file lwjgl.dll and lwjgl64.dll not being loaded, because I can't even find them in the .tekkit natives folder either. I tried copying the two .dll files from the .minecraft folder but still is a no-go.