Hi,
Macros that use \doifnextcharelse should all be defined
as \unexpanded, to prevent errors like:
\expanded{$\sqrt 2$}
Also affected are:
\decrement
\increment
maybe there are others, but these were easy to spot because
they were single-line \def's. The \sqrt is painful, because it
is likely to appear in \write-s
Cheers,
Taco