^ That is not a good idea.

The wallet doesn't scale well at all and despite the large amount of RAM you might be hitting a limit that is causing the bad alloc (although a bad alloc could also be caused through passing an invalid value for allocation).

To work out whether the problem is your wallet's size back it up and then delete it and re-start Bitcoin (it will create a new empty wallet). If no crashes happen with the empty wallet then I would assume your problem is the huge wallet.