I previously had 1.2 installed without any issues.
Decided to do a complete reinstall for 1.5. Deleted database and all WP folders.
Installation works fine but when I try to login with the admin username and password it seems to accept the password but redirects right back to the login screen (no errors). WP installed without errors.
This happens on all browsers (deleted cache, cookies etc).
Checked database values for 'home' and 'siteurl' and they are both correct.
Tried using the copy-paste method for wp-login.
I was able to reinstall 1.2 and it worked just fine.
Anyone have any ideas?