An easy way to beat a level (even on hardened) is to get your guys on the other side. in the beginning just send out riflemen and assault guys (or a tank and lots of riflemen if you can or when the enemy sends out a tank). after that just keep sending riflemen and some assault. the riflemen load quickly and cost as much as you get (200) so you can just send them over and over again. This is really helpful for the last 2 achievements!!
That's the first time we've heard of such problem. Do you have the latest flash player?