Question Redirect page after click submit

Hello,
i got the error page after clicking submit , but new topic or reply is successful shows in the forum.
it seems the problems is only rediect page after submit. Could anyone help?



Below is my setting.

Database collation check: The collation of your table fields are correct

Legacy mode: Disabled | Joomla! SEF: Enabled | Joomla! SEF rewrite: Enabled | FTP layer: Disabled |

This message contains confidential information

htaccess: Exists | PHP environment: Max execution time: 30 seconds | Max execution memory: 128M | Max file upload: 12M

Kunena menu details:

Joomla default template details : rt_ionosphere | author: RocketTheme, LLC | version: 1.3 | creationdate: April 10, 2012

Kunena default template details : Blue Eagle (default) | author: Kunena Team | version: 1.7.2 | creationdate: 2012-01-31

Kunena version detailled: Installed version: 1.7.2 | Build: 5215 | Version name: Omega | Kunena detailled configuration:

Warning: Spoiler!

[th]Kunena config settings:[/th]

board_offline	0
board_ofset	0.00
enablerss	1
enablepdf	1
threads_per_page	20
messages_per_page	6
messages_per_page_search	15
showhistory	1
historylimit	6
shownew	1
jmambot	0
disemoticons	0
template	default
showannouncement	1
avataroncat	0
catimagepath	category_images/
showchildcaticon	1
annmodid	62
rtewidth	450
rteheight	300
enableforumjump	1
reportmsg	1
username	1
askemail	0
showemail	0
showuserstats	1
showkarma	1
useredit	1
useredittime	0
useredittimegrace	600
editmarkup	1
allowsubscriptions	1
subscriptionschecked	1
allowfavorites	1
maxsubject	50
maxsig	300
regonly	0
changename	0
pubwrite	0
floodprotection	0
mailmod	0
mailadmin	0
captcha	0
mailfull	1
allowavatar	1
allowavatarupload	1
allowavatargallery	1
avatarquality	65
avatarsize	2048
allowimageupload	0
allowimageregupload	1
imageheight	800
imagewidth	800
imagesize	150
allowfileupload	0
allowfileregupload	1
filetypes	txt,rtf,pdf,zip,tar.gz,tgz,tar.bz2
filesize	120
showranking	1
rankimages	1
avatar_src	fb
fb_profile	fb
pm_component	no
userlist_rows	30
userlist_online	1
userlist_avatar	1
userlist_name	1
userlist_username	1
userlist_posts	1
userlist_karma	1
userlist_email	0
userlist_usertype	0
userlist_joindate	1
userlist_lastvisitdate	1
userlist_userhits	1
latestcategory
showstats	1
showwhoisonline	1
showgenstats	1
showpopuserstats	1
popusercount	5
showpopsubjectstats	1
popsubjectcount	5
usernamechange	0
rules_infb	1
rules_cid	1
help_infb	1
help_cid	1
showspoilertag	1
showvideotag	1
showebaytag	1
trimlongurls	1
trimlongurlsfront	40
trimlongurlsback	20
autoembedyoutube	1
autoembedebay	1
ebaylanguagecode	en-us
fbsessiontimeout	1800
highlightcode	0
rss_type	topic
rss_timelimit	month
rss_limit	100
rss_included_categories
rss_excluded_categories
rss_specification	rss2.0
rss_allow_html	1
rss_author_format	name
rss_author_in_title	1
rss_word_count	0
rss_old_titles	1
rss_cache	900
fbdefaultpage	recent
default_sort	asc
alphauserpointsnumchars	0
sef	0
sefcats	0
sefutf8	1
showimgforguest	1
showfileforguest	1
pollnboptions	4
pollallowvoteone	1
pollenabled	1
poppollscount	5
showpoppollstats	1
polltimebtvotes	00:15:00
pollnbvotesbyuser	100
pollresultsuserslist	1
maxpersotext	50
ordering_system	mesid
post_dateformat	ago
post_dateformat_hover	datetime
hide_ip	1
js_actstr_integration	0
imagetypes	jpg,jpeg,gif,png
checkmimetypes	1
imagemimetypes	image/jpeg,image/jpg,image/gif,image/png
imagequality	50
thumbheight	32
thumbwidth	32
hideuserprofileinfo	put_empty
integration_access	auto
integration_login	auto
integration_avatar	auto
integration_profile	auto
integration_private	auto
integration_activity	auto
boxghostmessage	0
userdeletetmessage	0
latestcategory_in	1
topicicons	1
onlineusers	1
debug	1
catsautosubscribed	0
showbannedreason	0
version_check	1
showthankyou	1
showpopthankyoustats	1
popthankscount	5
mod_see_deleted	0
bbcode_img_secure	text
listcat_show_moderators	1
lightbox	1
activity_limit	0
show_list_time	720
show_session_type	0
show_session_starttime	0
userlist_allowed	0
userlist_count_users	1
enable_threaded_layouts	0
category_subscriptions	post
topic_subscriptions	every
pubprofile	1
thankyou_max	10
email_recipient_count	0
email_recipient_privacy	bcc
email_visible_address
captcha_post_limit	0

Third-party components: None

Third-party SEF components: sh404sef: The file doesn't exist sh404sef.xml !

Plugins: System - Mootools Upgrade: Disabled | System - Mootools12: Disabled

Modules: None

Three points that I would like to make:

(1) We cannot access your website. Your website be hidden behind a firewall and it is not connected to the internet. In cases where we cannot actually view someone's website (for example, they may be running the site on their own PC or within a corporate intranet environment) please read our standard response in Support for PC-hosted websites (e.g. WAMP, XAMPP)

(2) Your image shows "Error 500" but the description looks like a HTTP 404 Page Not Found Error. Again, because we cannot visit your website, I cannot tell if the error relates to a HTTP 404 Page Not Found Error or whether it relates to a HTTP 500 Internal Server Error . One thing is sure. Your Joomla/Kunena menu is all wrong. Please read the FAQs page (at the top of this forum page) for How do I restore my Kunena menu?

(3) sh404SEF may be responsible for the page redirection that's occurring. sh404SEF can cause many problems if it's not used properly and, in extreme cases, it will eventually grind the performance of your website to a halt. If in doubt, uninstall sh404SEF and try again.

I hope this helps.

Hello,
thank you very much for help.
According to access my website. My domain is thai language, so i am not sure that is the reason of accessable.
please try to access my website by this link.

http://xn--42cga5cwdd3azx6b7br8ii8i.com/

I cannot access that page, sorry.