Fatal Error SG optimiser

Click here to see the error I keep getting on the above page when I try to log in as admin. It has been happening consistently on a weekly basis for the last month.
Here’s what a siteground support person said:
It looks like it is some kind of a plugin conflict between the SG optimizer and another plugin you might be having and one is blocking the functionality of the SG optimizer which then causes the SG optimizer to break. I cannot say the exact specific reason or plugin causing this. But it seems it causes the SG optimizer to freeze and flush its cache and only disabling the plugin and reinstalling it does the job.

The page I need help with: [log in to see the link]