Hiki Error

invalid byte sequence in EUC-JP (ArgumentError)
/home/arton/public_html/hiki/hiki/util.rb:63:in `gsub'
/home/arton/public_html/hiki/hiki/util.rb:63:in `escape'
/home/arton/public_html/hiki/hiki/db/flatfile.rb:240:in `textdir'
/home/arton/public_html/hiki/hiki/db/flatfile.rb:75:in `exist?'
/home/arton/public_html/hiki/hiki/db/flatfile.rb:61:in `load'
/home/arton/public_html/hiki/hiki/storage.rb:31:in `backup'
/home/arton/public_html/hiki/hiki/storage.rb:35:in `delete'
/home/arton/public_html/hiki/hiki/command.rb:58:in `rescue in initialize'
/home/arton/public_html/hiki/hiki/command.rb:52:in `initialize'
/home/arton/public_html/hiki/hiki.cgi:51:in `new'
/home/arton/public_html/hiki/hiki.cgi:51:in `block in <top (required)>'
/home/arton/public_html/hiki/hiki/storage.rb:14:in `open_db'
/home/arton/public_html/hiki/hiki.cgi:50:in `<top (required)>'
/home/arton/public_html/collabo/backyard/index.cgi:8:in `load'
/home/arton/public_html/collabo/backyard/index.cgi:8:in `<main>'