I'm at a dead end on this one - I've posted this in the PHP section as I believe it to be script related. If it's felt that this would be better placed in another section, please don't hesitate to move it. I'm using a shared hosting server, running php 5.25 (with set env php5 in htaccess) and mysqli 5.0.22 I'm using phpBB 3.2 as my forum with no mods except for some css changes to link the style to the main site. The main site is integrated for registration, log ins and sessions with phpBB. It all works well except for this current problem. Different users, using different browsers and doing different things, both in the forum and outside in other areas of the site, occasionally experience 403 Forbidden error pages coming up. These can be bypassed simply by refreshing the browser. When they happen they always happen at 5, 10, 15, ... up to 50, 55, 00 minutes - every 5 minute interval has had at least one on some occasion. Also they all occur within a band of 15 - 21 seconds after the minute. Since the 15th Oct, I have looged 16 of these errors and there have been no other errors like this outside of the time pattern. Another aspect is that the 403 pages are bog standard white ones and not the custom ones that htaccess points to. Also, the errors only show in the user logs - not the phpBB error logs or the server error logs. My server support team have looked into it and said there is nothing running on the server or within another domain on the server that would cause this - they referred me to phpBB support. PhpBB just say that it can only be a server problem. I'm in the middle and a bit lost. My feeling is that it's got to be a cron job but as my site is developing and increasingly being used, I don't want to fiddle blindly. I don't understand the cron side very much, along with the shutdown_functions and other code etc that could be at the root of this. I need a bit of guidance as to what to look into or some sort of advice when I could go back to the server crew or phpBB and get them to investigate from there. Thanking you, in advance for reading this.