PHP & IE8 bug

Open reportkdp1.php in IE 8:
a. Select a date & website
b. Then tick a book, click on Update Promo
c. Choose the date & website you selected in a. again, notice that the book you have checked in b. is still unchecked in browser, but the promo field in the database is already 1.

So I think the problem is browser cache ?
Note that it works fine on both Chrome & FF, just not on IE 8.

Also, I need help with setting up XAMPP, I am getting the following error:

Access forbidden!
You don't have permission to access the requested object. It is either read-protected or not readable by the server.
If you think this is a server error, please contact thewebmaster.
Error 403
localhost
1/28/2012 8:01:27 AM
Apache/2.2.14 (Win32) DAV/2 mod_ssl/2.2.14 OpenSSL/0.9.8l mod_autoindex_color PHP/5.3.1 mod_apreq2-20090110/2.7.1 mod_perl/2.0.4 Perl/v5.10.1