Users cannot join 7.0.4 site

I have tried to create a profile on the site and get to the bottom of the JOIN.PHP and then NOTHING. You can Press on the JOIN button and there is no action. This site was doing the same under 7.0.3, so without any members, I decided to bite the bullet to make the upgrade.

I have checked the profile fields, and nothing is out of the ordinary, so can someone please give some assistance?The URL is PrivateAdventures.com

Warning:
file_put_contents(/home/********/public_html/plugins/htmlpurifier/standalone/HTMLPurifier/DefinitionCache/Serializer/HTML/4.1.1,0fa6f510f367da3a203a9d2abb02f1b6,1.ser)
[function.file-put-contents]: failed to
open stream: Permission denied in
/home/**********/public_html/plugins/htmlpurifier/HTMLPurifier.standalone.php
on line 11186

A few things to try..

1. disable all caching from admin panel

2. clear cache via ftp or cpanel and not from admin panel ie: cache and cache_public folders

3. I guess checking the perms on the standalone.php file to make sure its right couldnt hurt...

4. switch back to the uni template and test join form again after 1,2, and 3 are done.

5.also getting a field min value error on education field even when its not required.

hope that helps.

SO far I have :

1) cleared all cache files via FTP

2) Disabled all caching in Admin panel

3) Moved to UNI template

4) Checked permissions on HTMLPurifier.standalone.php which are now set to 755 just to see if there is a difference

5) Scrolled through all permissions and ownership of folders and files, and all is consistent

Still no response from form as to whether it is posting, and no submission of JOIN.php

Not sure what to do next

I am thinking that it is a bug in the profile builder since I had created profile fields that did not show in the database themself under PROFILES table. I am ready to nuke this site and spend a week rebuilding! Or maybe just a wipe of all files and copy from backup of sister site? Truly the only thing that is crazy here is that the profile builder has show real bad headaches since 6.1.   Why can't there be an error checking to verify that when you create a profile field, that the system will post with a confirmation of successful update to the PROFILES table?  I can see that the block is created in the Profile Fields builder, but not written to the table of the profiles. Admittedly, if this is what is happening on the Private Adventures, then there needs to be an extra layer of error checking.

Now I have another site on the same server, which is identical in MODS and templates. I am able to join there and it is using the same files as the 7.0.4 upgrade path I did on this site.