Yes, lemme just check here from my magicbook of wellbeing what might cause it... Hmm... Yes...
It seems like one way to possibly fix this is by copying your console log to pastebin.com and giving us the link to that paste.
OR
You can try moving your FTB somewhere that's not in your downloads/desktop (for example, move your FTB launcher to c:/ftb), then start the launcher, go to options tab, change the path to c:/ftb, exit the launcher and restart the launcher.