If there is an HTML link like the following:

<a href="Page.asp?a=1&b=1">Link</a>

or

<a href="Page.asp?a=1&amp;b=1">Link</a>

then the ampersands are being replaced with &nbsp;

See "Links with ampersands" section on my test page:
<http://kauler.com/misc/httrack/>