Clarion Technologies on "Getting White Screen in Dashboard Posts and Pages Only"

I cannot access individual Posts nor Pages in my WordPress dashboard. Everything else seems to be working fine. In Safari I get a blank white page when I click on a post or page in the list. In Chrome I get an HTTP ERROR 500.

I have contacted support at Siteground. The tech told me he temporarily deactivated all the plugins, and he was able to access a post. He attached a screenshot. He directed me to start deactivating plugins, which I did, but then things started going crazy.

I would deactivate a plugin, and then I could access a post. Then the page would go white. So I would deactivate another plugin, and it would work, but then the same thing would happen again. I have now deactivated about eight or ten plugins, and this keeps happening.

I have no way of isolating a plugin with this happening. Please advise. Thanks!