[Typo3] Install problem testsite-3.8.0

[Jan]

Hi Everybody

I'm trying to install testsite from testsite-3.8.0.zip on Win XP with XAMPP.
I get the following error when i try to start: 

TYPO3 Fatal Error: Extension key "sv" was NOT loaded! (t3lib_extMgm::extPath)

This happen both when i try localhost/testsite and localhost/testsite/typo3
What to do?

I'm a total noob on Typo3, but i will try to make a multilang site, any tips are highly appreciated!

Regards
- Jan (jan_)

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