[TYPO3-english] typo3 4.4.6 install tool + Error: Session already started by session_start()

[J. Bakshi]

Dear list,

I am trying to upgrade typo3 4.4.1 to 4.4.6

but when visiting install tool I get

` ` ` `
Error: Session already started by session_start()

Make sure no installed extension is starting a session in its 
ext_localconf.php or ext_tables.php.

` ` ` `

I don't have ameos_formidable installed here. Any clue ?

TIA