Sorry, I didn't say correctly what happend. It doesn't report errors during compilation time, the program crashes when I run it. Compilation runs ok.

I didn't use unions, I just have four floats in the struct. I'll try as you suggested.

I don't want to bother everyone any further. Thanx everyone for help.
What I realy need is a good source to learn SSE from so if somebody could dirrect me to some I would appreciate it.

snippet from my blog:

So I asked the friendly community over at gamedev.net if they could knew of any assembly tutorials (mainly concerning SSE and MMX)... SSE isn't all that hard, pretty easy. If you really want to start learning it, read through these tutorials very quickly:

* http://www.neilkemp.us/v3/tutorials/SSE_Tutorial_1.html
* http://www.3dbuzz.com/vbforum/showthread.php?t=104753

And then, use this guide as a reference to available instructions:

* http://www.intel80386.com/simd/mmx2-doc.html