[horde] Troubles creating calendar entry

[Stephan]

Hi,

I am having troubles creating certain calendar entries in Horde 
Groupware Webmail Edition 5.0.2, this is what horde log says:

Creating default object from empty value [pid 17826 on line 52 of 
"/var/www/horde4/kronolith/new.php"]
array_merge(): Argument #2 is not an array [pid 22110 on line 50 of 
"/usr/local/lib/php/Horde/Support/Randomid.php"]
shuffle() expects parameter 1 to be array, null given [pid 22110 on line 
53 of "/usr/local/lib/php/Horde/Support/Randomid.php"]
implode(): Invalid arguments passed [pid 22110 on line 60 of 
"/usr/local/lib/php/Horde/Support/Randomid.php"]
Argument #2 is not an array [pid 22110 on line 50 of 
"/usr/local/lib/php/Horde/Support/Randomid.php"]
shuffle() expects parameter 1 to be array, null given [pid 22110 on line 
53 of "/usr/local/lib/php/Horde/Support/Randomid.php"]
implode(): Invalid arguments passed [pid 22110 on line 60 of 
"/usr/local/lib/php/Horde/Support/Randomid.php"]
HORDE [kronolith] SQL QUERY FAILED: SQLSTATE[23000]: Integrity 
constraint violation: 1062 Duplicate entry '1B2M2Y8AsgTpgAmY7PhCfg1' for 
key 'PRIMARY'

php is version 5.4.9.

Any hints ?

Regards
Stephan