Thanks, Livewire. I don't think it's just me receiving it. I posted the link on
Google Webmaster Forums (by request) and I believe the person who responded got the same message, as he was trying to help me figure it out:
Looks like it's the phising message you have, rather than malware
I'd previously tried disabling all my security to see if it was just me, but the only time it goes away if I disable 'block reported web forgeries' in Firefox. It's happening on both my main computer and laptop, running different operating systems. So puzzling. It's not in Google's blacklist database, not in stopbadware's, yet something is making some browsers believe otherwise.
At this point I think I'll just take the site offline for a bit, as I've had to publicly post the address in the Google forums in order to get assistance. It's a personal site I use mainly for therapy (art, design and writing), occasionally shared with only a handful of friends, and it's basically the one place on the web where my extreme social phobia doesn't make me panic and run away. For now I think it's best to retire for a while, since I seem to be the only one affected. Thanks again!
Edit: I had someone else check it via mobile and it loaded fine on the standard Android browser and on Chrome. I checked it on mine - loads fine with Opera mini. Same with Opera on the laptop (which I hadn't checked before, so no idea if it showed the original warning), but Firefox STILL shows the warning. Clearing browser cache doesn't seem to help. I'm waiting to have a friend load it in Firefox in a bit to see if that is where the problem is. (Note that the Firefox issue occurs for me on two separate computers, both of which I'd loaded the site when the issue was still current for the server.)
Edit 2: The user on Google Webmaster Forum
confirmed that he is getting the warning in Chrome.