Dear JC, most likely those are server configurations.
Make sure that permissions for directories are 755, files 644.
Exceptions:
ow_userfiles ( and all directories within) - 777
ow_static ( and all directories within)- 777
ow_smarty/template_c- 777
ow_pluginfiles ( and all directories within)- 777
Also please paste content of your main .htaccess file.
This also might be caused by mod_security rules. Try saving your changes with enabled Firebug or any other debug tool. If you see 403 forbidden message- then you will need to trigger mod_security server settings