[TYPO3-project-seminars] Exception in Module 'Seminars'

[Heinrich, Achim, HSZ]

Dear Friends,

when I choose module 'Seminars' and click on the SysFolder where my
Seminars are stored to get the registration statistics, I get the
following exception instead:

Fatal error: Uncaught exception 'tx_oelib_Exception_NotFound' with
message 'The FE user with the UID 1 could not be retrieved.' in
/srv/www/htdocs/typo3conf/ext/seminars/class.tx_seminars_registration.ph
p:302 Stack trace: #0
/srv/www/htdocs/typo3conf/ext/seminars/class.tx_seminars_registration.ph
p(419): tx_seminars_registration->retrieveUserData() #1
/srv/www/htdocs/typo3conf/ext/seminars/class.tx_seminars_registration.ph
p(541): tx_seminars_registration->getUserData('name') #2
/srv/www/htdocs/typo3conf/ext/seminars/mod1/index.php(302):
tx_seminars_registration->getUserNameAndEmail() #3
/srv/www/htdocs/typo3conf/ext/seminars/mod1/index.php(253):
tx_seminars_module1->generateEmailList('tx_seminars_att...') #4
/srv/www/htdocs/typo3conf/ext/seminars/mod1/index.php(214):
tx_seminars_module1->listSeminarDetails() #5
/srv/www/htdocs/typo3conf/ext/seminars/mod1/index.php(169):
tx_seminars_module1->moduleContent() #6
/srv/www/htdocs/typo3conf/ext/seminars/mod1/index.php(335):
tx_seminars_module1->main() #7 {main} thrown in
/srv/www/htdocs/typo3conf/ext/seminars/class.tx_seminars_registration.ph
p on line 302

It worked out fine before and I cannot remember to have changed anything
affecting this.
By the way I looked into the table fe_user and found that the FE user
with the UID 1 is still there...

Many thanks for your hints in advance
Achim