This is my first experience with OR however I have read through the forums and have tried to troubleshoot the issue but am still coming up short. I am attempting to install OR 2.5.7 and have uploaded it myhost/public_html/or/ and I have changed permissions according to the install documentation (tried both 755 and 777). When I go to mysite.com/or/install/index.php I get an error of 500 Internal Server Error. I'm thinking that because this is an internal server error there must be something wrong with my host... but for testing I used Fantastico De Luxe to successfully install OR 2.5.6 so obviously my host must be setup to work with OR... I also tried upgrading 2.5.6 to 2.5.7 and right away am faced with the 500 Internal Server Error.

So you ask that I check the error logs. Here is what I'm getting:
[Sat Jul 25 18:39:04 2009] [error] [client 67.159.44.51] File does not exist: /home/mysite/public_html/500.shtml, referer: http://mysite.com/or/install/index.php
[Sat Jul 25 18:39:04 2009] [error] [client 67.159.44.51] SoftException in Application.cpp:252: File "/home/mysite/public_html/or/install/index.php" is writeable by group, referer: http://mysite.com/or/install/index.php
I've tried with both the .htaccess file present and not present. Any help / suggestions would be greatly appreciated. Thank you!