So to clarify, patcher->game client doesn't work, but launching game client directly does?
If that's the case, are you running your patcher through a shortcut or directly from your RO folder? If you are, the "Start in" setting might be set to something other than your RO folder. That would be the only reason I can think of right now. It's also a pretty slim chance.

If it's not the case, I guess checking up on your system files wouldn't be too bad. If reinstalling your device drivers didn't work, you could try reinstalling DirectX. I've seen one case where that was actually the problem, but if the game runs fine, that shouldn't be it. If you want to try anyway, the link is here:
http://www.microsoft.com/downloads/en/details.aspx?FamilyID=2da43d38-db71-4c1b-bc6a-9b6652cd92a3&pf=trueThis whole case just seems really bizarre. I'm pretty sure it's something with Windows and not any RO files, but it's really hard to narrow down since the message that Gravity left in the client is so vague.