Seems like you and I have a similar problem.
http://www.promusicproducts.com/forum/p ... php?t=4382
Having notes that don't sound when you press them is very frustrating, and makes the keyboard useless. You should take solace, however, in the fact that your case is not isolated. You know of at least one other user in the same boat.
You have a brand new unit that is not working properly. Sweetwater should have caught this problem at the door, since they did all the upgrades. I've had mine for about a year and a half. I Installed the memory expansion myself and that's when all my trouble started. Hope I resolve it soon, though cause it's really holding me back. It just happens to often to be ignored.
You should be careful at this point about how you proceed, too. I wouldn't do anything to the hard drive either such as re-formating it, without backing it up. I'm not sure this would help anyways cause I think the problem is software. The reason I say this is because in my case, if I strike a key that is not sounding enough times, it will eventually sound but randomly. If the patch was missing a sample the Fusion would let you know, and wouldn't load it in to memory. Does this happen to you? I honestly think the issue is either the o.s. or the memory expansions.
Knowing what I know now, if I where in your shoes (within the return/exchange period), I'd send it back to sweetwater and ask for a repair or my money back. Good luck.
Alesis Fusion 8HD | Ibanez SR506 | Yamaha DTXtreme III | Logic Pro 6.4.3 | ...