"No Data Received" after Login Error

Hello,

We're having a problem on one of ours sites where after we try logging in, we get an error that says "No Data Received."

We've tried disabling all the plugins, switching to a default theme, everything. We contacted our host and they couldn't find any errors.

Any ideas on how to help fix this? We can't get into our wp-dashboard at all.

Thanks,

SM