Math rendering stops working

[cben]

Sometimes all rendering stops, until reload :-(

Object
render-math.js:46 34.382s typesetting $\ce{$ <span title=​"$\ce{$" class=​"inline_math cm-em cm-quote cm-quote-2" style=​"display:​ inline-block;​">​…​</span>​
render-math.js:46 34.394s done typesetting $\ce{$
render-math.js:53 34.394s CodeMirror.Posch: 28line: 7__proto__: CodeMirror.Posrender-math.js:53 error
render-math.js:46 34.395s unrendering math $\ce{$
render-math.js:46 34.395s typesetting $ -&gt;[\ce{+H2O}] $ <span title=​"$ ->[\ce{+H2O}​]​ $" class=​"inline_math cm-em cm-quote cm-quote-2" style=​"display:​ inline-block;​">​…​</span>​
render-math.js:46 34.449s done typesetting $ -&gt;[\ce{+H2O}] $
codemirror.js:5234 Uncaught Error: Inserting collapsed marker partially overlapping an existing one
render-math.js:53 34.879s Fallaback flushMarkTextQueue: 1 elements
codemirror.js:5234 Uncaught Error: Inserting collapsed marker partially overlapping an existing one
render-math.js:46 35.076s cursorActivity CodeMirror.Pos left unrenderedRange. Object