Why is this jQuery Validation not working on IE 7/8?

Why is this jQuery Validation not working on IE 7/8?

I'm encountering a small problem with a client-side validation script
which works on all browsers including IE 9 / 10, but is giving me
headaches on IE 7 and IE 8.
The page with the form which needs this validation can be accesed over
here and someone must definetly take a look in order to give a good
answer.
And here's the validation script I use for the form:
jQuery(document).ready(function(){
jQuery("#adaugareanunt").submit(function(event){
errornotice = jQuery("#eroareadaugare");
emptyerror = "Necompletat";
emailerror = "Email incorect";
email = jQuery('#contactEmail');
descriere = jQuery('#descriptionro_RO');
jQuery('#adaugareanunt input[type="text"]').each(function(){
if ((jQuery(this).val() == "") || (jQuery(this).val() ==
emptyerror)) {
jQuery(this).addClass("campuri-necesare");
jQuery(this).val(emptyerror);
errornotice.fadeIn(750);
} else {
jQuery(this).removeClass("campuri-necesare");
}
});
jQuery('#adaugareanunt select').each(function(){
if ((jQuery(this).val() == "")) {
jQuery(this).addClass("campuri-necesare");
errornotice.fadeIn(750);
} else {
jQuery(this).removeClass("campuri-necesare");
}
});
if(descriere.val() == "" || descriere.val() == emptyerror) {
descriere.addClass("campuri-necesare");
descriere.val(emptyerror);
errornotice.fadeIn(750);
} else {
descriere.removeClass("campuri-necesare");
}
if
(!/^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/.test(email.val()))
{
email.addClass("campuri-necesare");
email.val(emailerror);
}
if (jQuery(":input").hasClass("campuri-necesare")) {
return false;
}
});
// Clears any fields in the form when the user clicks on them
jQuery(":input").focus(function(){
if (jQuery(this).hasClass("campuri-necesare") ) {
jQuery(this).val("");
jQuery(this).removeClass("campuri-necesare");
}
});
});
Any hints?
Thanks!