False error message when logging in, "Cookies are blocked or not supported …"

Hi all,

I am developing a new wordpress site and want a login form on the front page. Only problem is that sometimes when I login in I am taken to the login page and get a message that says, “ERROR: Cookies are blocked or not supported by your browser. You must enable cookies to use WordPress.” If I click the back button to go back to the home page it shows that I have successfully logged in, so I don’t know why I am getting this message.

Here is the code I am using for my login form:

<form name="loginform" id="loginform" action="https://dev.sbceoportal.org/portal_beta/wp-login.php" method="post">
                            <!-- Username-->
                            <input value="Username" class="input" style="width: 75px;" type="text" size="20" tabindex="10" name="log" maxlength="40" size="13" id="user_login" onfocus="if (this.value == 'Username') {this.value = '';}" onblur="if (this.value == '') {this.value = 'Username';}" />

                            <!--Password -->
                            <input value="Password" class="input" style="width: 75px;"  type="password" size="20" tabindex="20" name="pwd" maxlength="40" size="13" id="user_pass" onfocus="if (this.value == 'Password') {this.value = '';}" onblur="if (this.value == '') {this.value = 'Password';}" />
                            <input name="rememberme" id="rememberme" value="forever" tabindex="90" type="checkbox"> Remember me?
                            <input name="wp-submit" id="wp-submit" value="Log In" tabindex="100" type="submit">
                            <!--<input name="redirect_to" value="https://xxx.com/wp-admin/" type="hidden">-->
                            <input name="testcookie" value="1" type="hidden">
                    Thanks,
Kristen
                 </form>