Snapshot Failing to Run Backup


I am using Snapshot Pro on this multisite installation to backup all the sites on the Network. I have a backup scheduled every week for each site, including the main site. Each backup is running fine with the exception of the main site, which appears to start and stop very quickly when run either on schedule or using the manual "run now" link.

From my PHP error logs, each time it attempts to run, I get 2 errors, one right after the other:

mod_fcgid: read data timeout in 45 second
Premature end of script headers: wp-cron.php

Can you please help with this? I have enabled support access. Please feel free to try and run these / change the snapshot settings, but please don't mess with any other plugins or settings as this network has live sites running on it.