Netscape Trouble

I've adapted someone else's calendar written in PHP to display radio buttons on available delivery dates (the following six days excluding Sundays). I've got two calendars next to each other, one for the current month and another for next month. My radio buttons migrate from one to the other just fine, however, when it's the last day of June and the first radio button is on the first of July (as it should be), the radio button on the first of July can't be selected in Netscape! No problem in IE. I have my </form> closing tag that Netscape requires that IE doesn't, so that's not the problem. Although my calendars are normally updating live, I've set them to think it's June 30th. You can see them at http://www.dallasbureau.com. Use the login of bluepl and the pw of snoopy. It's a work site, so feel free to enter orders and play around. Thanks for any help you can offer. Don Smith