
Before opening the document YAP gives me this message:

I usually compile to PDF via PS (to get PStricks-things through too), but when I do that with this document all the summation-signs, integrals and big parentheses disappear...
I use MikTeX via TecniXCenter on Windows Vista.
I've attached my preamble and a part of the assignment as a minimal working example.. Hope someone can see why the big signs dissapear from PDF - or interpret why I cannot print via YAP. (btw the minimal working example gives the error "4000 vs. 600" instead of "300 vs. 600" as the full assignment gives...)