I have ran into this same install problem: 'Can not initialise PHP session, please verify that your browser accepts cookies'
This is a fresh install of moodle version 2.0. I have tried all the suggestions and hacks and cannot get past the point in the install after the database has been configured.
I have checked Windows firewall and it is not the issue.
I have tried this in various browsers and on various machines and all get the same message both on Mac and PC.
I have verified all my paths for $CFG->dirroot, dataroot, and webroot and all are valid.
I have verified with my host the proper version of PHP and MySQL, and the .htaccess has been updated accordingly.
I am hosting on hostgator BTW. I am completely stumped as to why this won't work, and have been dealing with this off and on for three days now.
Any suggestions would be greatly appreciated. I will keep hacking around and report back with anything I find.