Cannot install many applications on 64-bit

[Jim in Chicago]

I'm running mint 14 (mate) on my desktop and mint 15 (cinnamon) on my laptop, both 64-bit.
When trying to install a lot of packages I'm getting unmet dependancies which usually boil down to "packageA requires packageb and packageb is not installable, no install candidates"
The most recent is the 64-bit linux hamachi client, which depends on lsb-core...which is not installable.
It seems a lot of python packages are on the 'not installable' list, too.
My research thus far indicates that most of this nonsense is due to the change to multiarch (and, yes, I have set both systems for multiarch with i386 enabled)
The package before this was musicbrainz-picard. Did the same thing with uninstallable packages on my mint 14 64-bit machine. I needed the package up and running so installed mint 15 32-bit as a virtualbox machine and the program installed instantly and works fine.
I'm not sure what all is going on behind the scenes with this multiarch stuff, but it didn't seem to be broke until someone decided to fix it, and the end result is that a GREAT many programs (including 84-bit packages) are broken on 64-bit versions of mint.
I'm not sure why there aren't more bug reports on this, as I've verified that the problem occurs on 2 different versions of mint on 2 different machines. Off the top of my head, here are the affected apps: Hamachi, Sabnzbd+, Musicbrainz-picard, newsflash, and there have been a host of others that I've come across in researching this problems but I haven't kept a list.

Just my opinion, but considering that this prevents installation of many packages on the most up-to-date (i.e. 64-bit) hardware, this should be a critical or high-importance bug. I shouldn't have to install a 32-bit OS on my 64-bit hardware. I thought we were past that. Thanks.