From http://en.wikipedia.org/wiki/Stack_overflow
In software, a stack overflow occurs
when too much memory is used on the
call stack. The call stack contains a
limited amount of memory, often
determined at the start of the
program. The size of the call stack
depends on many factors, including the
programming language, machine
architecture, multi-threading, and
amount of available memory. When too
much memory is used on the call stack
the stack is said to overflow,
typically resulting in a program
crash. This class of software bug is
usually caused by one of two types of
programming errors.
- Infinite recursion
- Very large stack variables
When this error is thrown, recursion is the more popular reason.
I've tried the site in IE8 without problems, so perhaps it is an old version of IE causing a problem.