Odd error

[swarfega]

I was working on my website when it ceased loading and all the browsers I tried reported this error:

Error 330 (net::ERR_CONTENT_DECODING_FAILED): Unknown error

I read that adding $config['output_compression'] = false; could be some fix to which it was. It brought back the website but it had an error at the top of the page:

Warning: session_start() [function.session-start]: open(/tmp/sess_1fe35949456cd4a683034b025088f3db, O_RDWR) failed: Permission denied (13) in /var/www/vhosts/thriplow.org.uk/httpdocs/cms/include.php on line 42

I checked permissions on /tmp (I assume this is the one in the cms folder) and they were 755. I changed this to 777, but the error still remains.

How can I fix this please.

[Using cmsms 1.10.3]