Why won't tikz work? [closed]

Question

I've been trying to use the tikz package but it won't work. I'm using TeXworks and when I try something basic like:

\documentclass{article}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
\draw (0,0) --(1,2);
\end{tikzpicture}
\end{document}

And I get the error message:

miktex-pdftex.exe: Cannot start MiKTeX package manager.
miktex-pdftex.exe: Data: Invalid syntax

! LaTeX Error: File `tikz.sty' not found.

I've tried the update feature on MikTeX and using the Package Manager that comes with MiKTeX (and there was no tikz.sty package there) but have had no luck, and get the same message.