400 Error -.. A sequence that could mean a hacker attack..

Hello all,

I’m getting this error when people visit my site at https://inandoutaz.com

It goes away when they clear their browser cache, but this magazine’s readership isn’t always browser savvy and keep sending me emails saying the site was hacked into.

I’ve been researching for a way to fix this, but I’m not sure what is causing it. We are on dreamhost and I think it’s on there end with a security setting or something, but their support is ATROCIOUS and so far after nearly 24 hours their only response was to say they’ve moved my support ticket to someone else more familiar with the problem.

Any help would be greatly appreciated.