I'm using the default userstring, today not only am I getting the cloudflare thing, but it is crashing the browser, simply vanishing at first, then when I tried a new profile, crashed recursively, 10 trp files, all sigaborts. Finally tried the Qt5 build and still got stuck in the loop of it checking and failing.
It was on the SeaMonkey newsgroup, alt.comp.software.seamonkey now as Mozilla shut down its newsgroups, that people were blaming the lack of WebGL support for the cloudflare problems.