For some reason LaTeX and adobe reader 9 don't get along.
Normally, I code my document in Latex, hit compile, and it makes the pdf and has reader open the document for viewing.
However, after updating to reader 9.3 I started getting error messages saying the document could not be opened every time a document compiled. The documents still compiled, and I could still go and open the document in reader manually, but for whatever reason reader and Latex could no longer communicate.
I solved this problem by rolling back to adobe reader 8.11. The problem persisted in reader 9.2, 9.1 and 9.0.