There is a related problem that might be what you're experiencing. If you attempt to solve a cloth system that becomes unstable it effectively renders that particular solver dead - it remains in an unstable state and does not attempt to solver further. There's no recourse for it that I've been able to find apart from creating a new solver or restarting Maya.
I've never had a problem with the delete cache causing the same problem. But unstable solves will do it. Perhaps that's what happened to you? Turning off adaptation control in the solver AE has helped reduce these occurrences for me.