Site freezes if CSS has parse errors

Autoptimize (well, the css optimizer AO uses) has no real knowledge of CSS, it’s just a somewhat-careful whitespace-remover with some extra’s thrown in. As such, if one of your source CSS-files has a parse error, it will indeed likely be present in the aggregated CSS as well and -depending on your browser CSS rendering engine’s forgiveness or lack thereof- it could break all CSS after it. This, I’m afraid, is not something that will change soon I’m afraid (unless I find a good PHP CSS-optimizer that really knows CSS, but don’t hold your breath) …

hope this clarifies,
frank