Hi,
I've just found this error the hard way. Any chance of getting a fix
from upstream?
A workaround for the current situation:
\let\RescueRightarrow=\Rightarrow
\usepackage{marvosym}
\renewcommand{\Rightarrow}{\RescueRightarrow}
(taken from
http://www-user.tu-chemnitz.de/~uro/teaching/WS2003-algebra-I/misc/blitze.pdf)
Regards,
Thomas