Treebeard

I have the same issue (- i.e. Arma2 "has stopped working" in the tick box section, 2 ticks from completion). It always happens when launching the release 1.62 arma2oa.exe (version 1.62.95.248). It didn't happen before the 1.62 patch. The beta versions work fine, so I use them for launching arma2 since the release of 1.62. This issue is not an isolated user's crash. This bug is pretty severe and needs fixing (- even though it is possible to work around by launching the beta version instead). I have the non-steam version of Arma2 by the way. OS: Windows 7 Pro 64-bit. Link to my crash files: http://dl.dropbox.com/u/22948126/ArmA%202%20OA.rar

Update: We got it to work by bypassing the wireless router on Froggy's side. So it seems something was not being handled properly on the router.

Me and FroggyLuv also encountered this issue on Friday evening (two days ago). We could not connect to each other's PCs. We could connect to many other public servers in the list though. The error was the same as yours (NAT Negotiation failed (NNThink - result 3)). It has worked fine previously but now it's not working by some odd reason. We tried both vanilla Arma2CO with and without beta and i44 with and without beta. Nothing impacted the "connecting failed" problem. Any advice on this issue would be welcome.