Dojo 1.3.1 upgrade rises isChecked() method issue under IE

I used Dojo 1.2.3 but it didn’t submit forms by clicking Enter or
Space on a submit button. I found out that it was a Dojo issue and it
was fixed in the latest releases. So, I upgraded Dojo to 1.3.1. The
upgrade fixed the issue of submitting a form by keyboard  and works
very well in Firefox 3 but it breaks the isChecked() method and
doesn’t work at all under IE 7 because of  the below difference in
POST data:

FF3:

array(4) {
…
["btn_search"] => string(6) "Search"
}

IE7:

array(4) {
…
 ["btn_search"] => string(304) "<SPAN class="dijitReset dijitInline"
dojoAttachPoint="iconNode" unselectable="on"><SPAN class="dijitReset
dijitToggleButtonIconChar" unselectable="on">✓</SPAN></SPAN><SPAN
class="dijitReset dijitInline dijitButtonText" id=btn_search_label
dojoAttachPoint="containerNode" unselectable="on">Search</SPAN>"
}

Does anybody know a workaround for it? Many thanks in advance.