[webkit-dev] Build error on windows

[bullet dummy]

Hello.

I'm tring to build the WebKit on Windows.
Installed Visual Studio 2005 Express, Cygwin(with bison, curl,
flex, gperf, make, patch, perl, perl-libwin32, openssh, svn, unzip and gcc).
And execute "perl WebKitTools/Scripts/build-webkit" on command prompt.
But error occured in file, "WebCore/css/makevalues".
The error message is
"27 input keys have identical hash values, examineout put carefully...
 Empty input key is not allowed.
 To recognize an empty input key, your code shouldcheck for
 len == 0 before calling the gperf generated lookup funciton.
 make: *** [CSSValueKeywords.h] Error 1"
What Do I do for this?