Performance issues?

Hello all,

I am having this weird problem in Unity3D at the moment. Sometimes when I start it random stuff will start to whine, like a few days ago I started it up and it could all of the sudden not use one of the scripts, and complained about each and every line in it.

Now later, mechanim gives me some warnings about finding bones in animations I dont even have in my game.

But what I wanted to talk about was the most recent performance issues. It was working fine, until one day, that's today, when it thought of to complain about first;

1. The DirectX level. Mine is set to DX11 and I am running DX11 games just fine, also NVidia says that my Geforce GT420 is compatible with DX9, DX10 and DX11. But Unity finds that to be a problem and strains against it.

2. I get some warning stuff in my shaders which tells me that shaders "Might be expensive on this platform". That is very weird. It wasn't so expensive a few days ago. But now all of sudden? It suggests me to use the "Mobile Shaders".

3. I just find something quite odd with the scripts too, I have made an object disappear upon clicking it. It just triggers a bool value, but this never got to work. That's odd, everyone else gets it to work just fine.

4. Also, I don't know if this is also related to the shader problem above, but my entire scene as of today is dark, and the shaders behaves oddly.

So in conclusion, give me one reason not to uninstall Unity and never look back. I am a long time user of it. But these random death-blows drives me mad. And I must spend my valuable time that I have aside of work, to deal with silly stuff like this instead of working on the game.

Thanks,