I get a similar error as above and have tried the above solution. I've requested the upgrade, deleted the original file I just bought and reinstalled the fresh build. Same problem. I have 2 sites and tried it on both. The first one is in the root folder and the second site is a subdirectory.
Jeff
Warning: session_start() [function.session-start]: open(/home/users/web/b1843/ipg.doggonebbqsaucecom/cgi-bin/tmp/sess_c694a19143e6e082647747ebc4fb4f4c, O_RDWR) failed: No such file or directory (2) in /hermes/bosweb25a/b1843/ipg.doggonebbqsaucecom/wp-content/plugins/wp-affiliate-platform/wp_affiliate_platform1.php on line 8