Update DirectX Drivers and download the follow redistributables. I don't know the specific one for FF14 but many applications use these and it doesn't hurt to install them (asides from HDD space).

I would think that FF14 is done with this one: http://www.microsoft.com/en-us/downl...s.aspx?id=5555 MSVC++ Redist (2010)

It could also be http://www.microsoft.com/en-us/downl...ils.aspx?id=29 MSVC++ Redist (2008) though

If all else fails try http://www.microsoft.com/en-us/downl....aspx?id=30679 MSVC++ Redist (2012) although I don't think they built FF14 off this given the time span.

Also (and I know this sounds like nagging) run through your Windows Updates as it's supposed to download the above for you when updates are detected.

As for why the game ran slower on your external HDD versus your internal this is because USB is extremely slow and unless your using eSata I wouldn't recommend that for any game, especially an MMO as it needs to constantly read from the disk drive. Also your GPU is on the super-low end spectrum and FF14 requires a fairly descent GPU to run the game. I would recommend if you own a PS3 to get that version over the PC one unless you want to upgrade your machine.