PLEASE HELP with Windows Install

I try install wordpress 2.0 on windows XP local PC. WordPress 1.5.2 working very good on this server. But after install WP2 and trying /log-in.php i look only 1 string “…may be not install, please run install.php…”. And i cant access to admin panel too. When try run install.php i look “…already installed…”. Sometimes when repeting installing more and more i can access to login screen only one time. On the Internet hosting all OK (i was uploading local directory WP2 and install it).
What is it mean? Why WP2 cant work locally???
(unzip, create folder, config.php, database no problem)