Seems to have rectified itself! All sites back up again with no action on my part.
Time for bed! 
Hi there -
All the sites on one of my reseller accounts (hosted by Clook) have gone down.
Nothing on any of these sites has been changed in months.
Error messages are all the same:
Warning: session_start() [function.session-start]: open_basedir restriction in effect. File(/home/madcap/tmp) is not within the allowed path(s): (/home/xxxxxxxxxxxxxx:/usr/lib/php:/usr/local/lib/php:/tmp) in /home/xxxxxxxxxxxxxx/public_html/manager/includes/config.inc.php on line 59
Fatal error: session_start() [<a href='function.session-start'>function.session-start</a>]: Failed to initialize storage module: files (path: ) in /home/xxxxxxxxxxxxxx/public_html/manager/includes/config.inc.php on line 59
Contacted the host, got back:
These sites are down because they are attempting to access a tmp folder that is outside of the account directories. You will need to correct this in order for them to work.
What can I do to get the sites back up?
