Here's the latest word on frozen foods - it can be kind of tricky following manufacturers’ instructions (given that we all have different models of microwave); if you don't do a good job, the results will really make you fall ill. We’ve been seeing reports of illnesses (salmonella and the like) from poorly microwaved frozen foods for quite a few years now. It got so bad at one point that about three years ago, the government issued health warnings for frozen foods. As far as researchers are concerned, people should forget about microwaves altogether for anything other than reheating food.
Why are microwaves unsuitable? Of course, there is the problem that people have different kinds of microwave and manufacturers kind of make it difficult for people to really understand how intensely they are nuking their frozen foods. But more importantly, microwaves, by their very nature, are unable to heat anything evenly. Everyone knows about how you can place something in a microwave and find cold spots, warm spots and hot spots after what seems like a thorough session in the microwave.
Most food safety experts will tell you that using a microwave to cook meat that is raw is never a good idea. Microwaves don't really do this very well. The problem is, that people don't really adequately understand that frozen food is completely raw food a lot of time. Since freezing happens to be a kind of processing, people somehow seem to assume that there's been a good bit of cooking already done. And that's not really true in many cases - people just pick up their packages of frozen food and they stick them in the microwave like all they need to do is to heat it up a bit. What they are dealing with is raw animal products - and these carry all kinds of dangerous diseases. Everyone's aware of how pork and other kinds of meat need to be cooked very thoroughly to get rid of all the parasites. And yet, somehow impressed with technology or something, they just cook frozen meat unevenly and inadequately, and don't realize what they're doing.
The message therefore is clear. You need to put a lot of research into how to cook frozen foods. It doesn't matter what you get frozen - if it has any animal products at all, the microwave isn't a good idea.