problem solved, it was somehow a problem with my .htaccess file.
I had permalinks activated, de-activated it, activated again, created a new htaccess file, and it worked again 
yes, I did. and I checked again with the new default template, still not working. so it can’t be really a theme issue, or?
edit: yes, my theme is in the my-templates folder (now)
thanks chris, this is my problem.
in my rss2.php in my themes folder I have the following line:
<pubDate><?php bb_post_time('D, d M Y H:i:s +0000'); ?></pubDate>
this is giving me this result:
<pubDate>Mo, 05 Jan 2009 21:58:55 +0000</pubDate>
but in the same file, the line:
<pubDate><?php echo gmdate('D, d M Y H:i:s +0000'); ?></pubDate>
is working fine. output:
<pubDate>Mon, 05 Jan 2009 23:24:47 +0000</pubDate>
I have: define('BBDB_CHARSET', 'utf8'); in my bb-config.
and I already use 1.0-alpha-4.1 of the bbPress Integration plugin.
ok, this problem is now back, after I updated to wp 2.7 and bbpress 0.9.0.3.
now my feed doesn’t validate because of the date:
Sorry
This feed does not validate.
*
line 18, column 39: pubDate must be an RFC-822 date-time: Fr, 02 Jan 2009 10:57:20 +0000 (35 occurrences) [help]
<pubDate>Fr, 02 Jan 2009 10:57:20 +0000</pubDate></blockqoute>
and the rss widget doesn’t update again with new forum postings.
yes, that seems to fix it (at least for me):
from this thread: https://wordpress.org/support/topic/188964/page/2#post-803992
go into your wp-config.php
and add this line:
@define(‘ADMIN_COOKIE_PATH’, ‘/’);
NOTE ‘/’ will be your blog path.
If you find that ‘/’ doesn’t work, make it ‘/blog/` or whatever your path is.
thanks chris for the help, that did the job. since the rss feed was displaying fine in FF, I didn’t thought about validating it.
ok, the problem is suddenly back. the rss feed isn’t updating in the widget anymore.
just upgraded to 0.9.0.2, and it’s working again. not sure if it was the bbpress update or the 2.5.1 wordpress update.
oh, of course (how could I miss that?), thank you!
