Here's how to get out of cron job hell
Ed,
As you've speculated, looks like your cron is not reading php. My guess is that you need to enter the appropriate php shell path. You may want to post your cronjob entry so we can see what you have.
Below is one way I can get an error like yours on my server:
*/5 * * * * /pathtoinstallation/support/api/cron.php
When I use this entry I get the same error as you've posted above. The cron.php file is not being parsed as php but just as a text file. So your cron is just reading each line looking for an appropriate command.
Below if I give the cron.php the appropriate directive, it will execute as expected:
*/5 * * * * /usr/local/bin/php /pathtoinstallation/support/api/cron.php
In the example above, I've included the absolute path to php (highlighted in green). There are a few other ways to do this but this is pretty easy and you don't have to modify any osticket files.
Now it's important to note that your server may have a different path for php. In that case, you can contact your host administrator for additional details.
I hope that helps.
Best Regards,
sg