Error Uploading Image To Field

[Smokebelch]

Can anyone help please? I'm trying to upload a small image (75x75), into a field & I'm getting the following error message: Fatal error: Maximum execution time of 30 seconds exceeded in /var/www/vhosts/mysite/httpdocs/libraries/joomla/filter/filterinput.php on line 429
I've checked to make sure everything's writable & it appears to be. Any ideas please?
Thanks in advance.