Actually in links "&" should be encoded as "& amp;" (without space)
It is not properly converted by the site, I should fix that, but it is not normal that the web browser converts "& curren" to the symbol: he should only do that for "& curren;" (with the ";")
Previously only IE had that behaviour, which caused sometimes problems with links with a "& lang" parameter (quite common) since "& lang;" is for an angle symbol.
Firefox added the acceptation of the symbols without the mandatory ";" to be more compatible with poorly made sites, but then it breaks compatibility with sites which make some less-dramatic errors like not converting "&" to "& amp;"