php.ini, eGroupware und Typo3

Hallo zusammen,

ich habe mal wieder eine Frage, un zwar:
Ich möchte gerne "eGroupware" installieren, jetzt kommt aber bei den Installationstests, dass ich in der php.ini
den auskommentierten mbstring.func_overload = 7 auf 7 setzen bzw. in meinem Fall den kommentar entfernen soll.
Mach ich natürlich, kein Problem...

Doch jetzt spinnt meine Typo3-Installation, indem ich mich nicht mehr anmelden darf und zwar sagt er mir dann dies hier:

Warning: mb_strstr() [function.mb-strstr]: Empty haystack in /var/lib/typo3-dummy/typo3conf/temp_CACHED_psda75_ext_localconf.php on line 161

Warning: mb_strstr() [function.mb-strstr]: Empty haystack in /var/lib/typo3-dummy/typo3conf/temp_CACHED_psda75_ext_localconf.php on line 163

Warning: Cannot modify header information - headers already sent by (output started at /var/lib/typo3-dummy/typo3conf/temp_CACHED_psda75_ext_localconf.php:161) in /usr/share/typo3/typo3_src-4.0/t3lib/class.t3lib_userauth.php on line 311

Warning: Cannot modify header information - headers already sent by (output started at /var/lib/typo3-dummy/typo3conf/temp_CACHED_psda75_ext_localconf.php:161) in /usr/share/typo3/typo3_src-4.0/t3lib/class.t3lib_userauth.php on line 312

Warning: Cannot modify header information - headers already sent by (output started at /var/lib/typo3-dummy/typo3conf/temp_CACHED_psda75_ext_localconf.php:161) in /usr/share/typo3/typo3_src-4.0/t3lib/class.t3lib_userauth.php on line 313

Warning: Cannot modify header information - headers already sent by (output started at /var/lib/typo3-dummy/typo3conf/temp_CACHED_psda75_ext_localconf.php:161) in /usr/share/typo3/typo3_src-4.0/t3lib/class.t3lib_userauth.php on line 314

Warning: Cannot modify header information - headers already sent by (output started at /var/lib/typo3-dummy/typo3conf/temp_CACHED_psda75_ext_localconf.php:161) in /usr/share/typo3/typo3_src-4.0/typo3/template.php on line 613

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /var/lib/typo3-dummy/typo3conf/temp_CACHED_psda75_ext_localconf.php:161) in /usr/share/typo3/typo3_src-4.0/typo3/index.php on line 240

Was kann ich tun, damit beides funktioniert? Ich hoffe das geht überhaupt.
Vielen Dank schon einmal für kommende Antworten.

Viele Grüße
Thorsten