I've downloaded the game installer twice (thanks for deleting it without asking that was nice to have to download a 20 GB installer twice in one day) and installed the game twice.
Each time I've downloaded the 1.7GB patch file (twice on that, just to be sure the patch wasn't corrupted) and both times the patch renders the game unable to launch.
I am able to play the unpatched game with no problems, but each time I run the patch, I get the following error:
It says that the program can't run because LeadD3DXenon.dll is missing from my system. It recommends a reinstallation.
Playing unpatched now but would appreciate any help anyone could provide regarding this issue.