Instiki won't run

Downloading http://rubyforge.org/frs/download.php/53354/instiki-0.16.5.zip ..
Downloading http://de.mirror.rubyforge.org/instiki/instiki-0.16.5.zip (7425011 bytes) ..
Received 1024 bytes (0 %)
Received 743424 bytes (10 %)
Received 1485824 bytes (20 %)
Received 2228224 bytes (30 %)
Received 2970624 bytes (40 %)
Received 3713024 bytes (50 %)
Received 4455424 bytes (60 %)
Received 5197824 bytes (70 %)
Received 5940224 bytes (80 %)
Received 6682624 bytes (90 %)
Received 7425011 bytes (100 %)
.. download complete.

Installing Ruby Gem mongrel ..
.. done
Installing Ruby Gem sqlite3-ruby ..
.. done

Now installing Instiki version 0.16.5 ..
Mongrel server did not start :
** Ruby version is not up-to-date; loading cgi_multipart_eof_fix
!!! Path to log file not valid: log/mongrel.log
mongrel::start reported an error. Use mongrel_rails mongrel::start -h to get help.
.. failed! See the error message above for the reason why.

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So, I guess one problem is Ruby not being up to date, I don't see any updater?

Second problem is the Mongrel log, but maybe thats because of #1?