WP-Super-Cache and 403 errors

In anticipation of a big traffic spike, I set my WP-Super-Cache settings super high. Since then the site has been wonky, with two main problems:

a) Readers who commented frequently started getting 403 errors, for no apparent reason.

b) Pages that I had updated no longer refresh, no matter how many times I clear the cache. I’m not even seeing the “Edit” button on the page. I suspect this is happening because I added some pages to be directly cached by WP-Super-Cache.

I have since reset the plugin settings to default — then when nothing happened I turned off caching — and then I deactivated the plugin entirely. No dice — readers still get the 403 errors, and I still can’t see the updated pages. Do I need to uninstall the entire plugin and edit my root code?

Any help is appreciated — thank you!