Question Suddenly: only a white page

I upgraded kunena to 1.6.3 and everything worked fine for about 11 days. Today all I get is a white/blank page when opening the forum.
I already checked all the steps in: Start by lookin this doc : docs.kunena.org/index.php/How_to_diagnose_blank_page_on_kunena

But all I seem to get is a white page.
Nothing has been changed to the site today or yesterday. All was working fine after the update 12 days ago.

I even tried a reinstall of Kunena, but nothing seems to help.

Can someone please help.

My configuration:

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

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

This message contains confidential information

htaccess: Exists | PHP environment: Max execution time: 30 seconds | Max execution memory: 64M | Max file upload: 20M

Joomla default template details : vinkeniera3 | author: Pinano | version: 1.3 | creationdate: 2010-12-31

Kunena default template details : Blue Eagle (default) | author: Kunena Team | version: 1.6.3 | creationdate: 2011-01-31

Kunena version detailled: Installed version: 1.6.3 | Build: 4344 | Version name: Parlare | Kunena detailled configuration:

Warning: Spoiler!

[th]Kunena config settings:[/th]

board_title	De Vinkenier
board_offline	0
board_ofset	0
offline_message	<h2>Het forum is momenteel off-line wegens onderhoudswerkzaamheden.</h2> <div>Komt u later nog even terug!</div>
enablerss	0
enablepdf	0
threads_per_page	25
messages_per_page	20
messages_per_page_search	20
showhistory	1
historylimit	10
shownew	1
jmambot	0
disemoticons	0
template	default
showannouncement	1
avataroncat	1
catimagepath	category_images/
showchildcaticon	1
annmodid	62,63
rtewidth	450
rteheight	750
enableforumjump	1
reportmsg	1
username	1
askemail	0
showemail	0
showuserstats	1
showkarma	0
useredit	1
useredittime	0
useredittimegrace	600
editmarkup	1
allowsubscriptions	1
subscriptionschecked	0
allowfavorites	1
maxsubject	60
maxsig	300
regonly	0
changename	0
pubwrite	0
floodprotection	0
mailmod	0
mailadmin	0
captcha	1
mailfull	0
allowavatar	1
allowavatarupload	1
allowavatargallery	1
avatarquality	65
avatarsize	2048
allowimageupload	0
allowimageregupload	1
imageheight	640
imagewidth	640
imagesize	200
allowfileupload	0
allowfileregupload	1
filetypes	zip,txt,doc,gz,tgz
filesize	250
showranking	1
rankimages	1
avatar_src
fb_profile
pm_component
userlist_rows	50
userlist_online	1
userlist_avatar	1
userlist_name	0
userlist_username	1
userlist_posts	1
userlist_karma	0
userlist_email	0
userlist_usertype	0
userlist_joindate	0
userlist_lastvisitdate	0
userlist_userhits	1
latestcategory	0
showstats	1
showwhoisonline	1
showgenstats	1
showpopuserstats	1
popusercount	10
showpopsubjectstats	1
popsubjectcount	10
usernamechange	0
rules_infb	1
rules_cid	16
help_infb	0
help_cid	1
showspoilertag	0
showvideotag	1
showebaytag	0
trimlongurls	1
trimlongurlsfront	40
trimlongurlsback	20
autoembedyoutube	1
autoembedebay	0
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	categories
default_sort	asc
alphauserpointsnumchars	60
sef	1
sefcats	0
sefutf8	0
showimgforguest	0
showfileforguest	0
pollnboptions	8
pollallowvoteone	1
pollenabled	1
poppollscount	5
showpoppollstats	1
polltimebtvotes	00:15:00
pollnbvotesbyuser	100
pollresultsuserslist	0
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	joomla
integration_login	joomla
integration_avatar	kunena
integration_profile	kunena
integration_private	uddeim
integration_activity	alphauserpoints
boxghostmessage	1
userdeletetmessage	0
latestcategory_in	1
topicicons	1
onlineusers	1
debug	0
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	1

Third-party components: AlphaUserPoints: Installed (Version : 1.5.13) | CommunityBuilder: Disabled or not installed | Jomsocial: Disabled or not installed | UddeIm: Installed (Version : 2.3)

Third-party SEF components: sh404sef: Disabled or not installed | ARTIO JoomSEF: Disabled or not installed | AceSEF: Disabled or not installed

Plugins: System - Mootools12: Disabled | System - Mootools Upgrade: Enabled | JFirePHP: Disabled or not installed | Kunena Discuss: Enabled (Version : 1.6.2) | Kunena Search: Disabled or not installed | My Kunena Forum Menu: Disabled or not installed | My Kunena Forum Posts: Disabled or not installed

Modules: Kunena Latest: Enabled (Version : 1.6.2) | Kunena Stats: Disabled or not installed | Kunena Login: Enabled (Version : 1.6.2)

Hello,

Do you have looked in apache/php log if you see something ?

I looked in the access.log and error.log provided with my hosting package. But don't seem to find anything. What should I be looking for?
or what do I need to provide for you to be able to help me out on this one?

When I totally disable the in joomla includes seo settings I can get to the frontpage of the forum. But i can't access the topics... Nor do the links seem to work. All these settings have been working fine for over a year.

I have a backup from my complete site that's 7 days old. How can I after restore of this backup see to it that I have all the recent topics in kunena? Can i simply export the complete database and then import it again after te restore of the site?

I found on the forum that you can do a downgrade. So I reverted back to kunena 1.6.2 from 1.6.3 and all is working fine again now.

I upgraded again, 7 days ago, to kunena 1.6.3 and all was working fine. Now I get the same problem: white page!
I upgraded tot kunena 1.6.4 and the problem persists: again only a white page when I open kunena.
Can someone please help?