i also had kopi running perfectly on win98 (SE, localized version).
i also had problems, but making directories solved them.
but i also had several QT dlls already, and cygwin if that matters, so dont take me as an example.
before reinstalling windows (which might or might not solve it),
try using "dependency walker" (by microsoft). it tells you if there are missing DLLs or other dependencies for any EXE or DLL.