Got news from Thomas Simonson (Project administrator - Department of Biology, Ecole Polytechnique).

The server is offline since 1 day now and the website is down too.
The administrators will try to fix the hardware problem tomorrow but the server will be probably offline until Monday.
Thanks for your patience.

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edit :
Is it possible this info on your main page ?
Would be nice and useful for the Proteins@home users
thanks
Nightbird