I recently had to reinstall windows onto my computer, due to it being windows. When done, I found that my portable drive had it's name changed from G: to F:. Not a big thing, I thought, until I ran into problems running Fallout. After some errors, I deleted the game folder and re-insalled it on my main (c:) drive. Reinstalling all the DLC took some time, and as I was finishing up I got a new copy of the 1.7 patch and set it to run while I tried to track down all my old mods.
Then I got the error message
"Fallout3.exe - Ordinal not found.
The ordinal 5360 could not be located in the dynamic link library xlive.dll"
...

I've never seen this error before. But it seems to like me, as now I cannot even play the game, as this error pops up whenever I try.
How did this happen, and how do I fix it? Can/should I change the external drive back to G:? Is there some small file from the first game that hid from the purge that is playing a gurrilla war on my system for revenge? If any assistance can be given I would appreciate it, as I cannot play the game in any shape or form at this time.