One other thing would be to disable Predict network actions to improve page load performance just to try and enable it again if problem persists.
You could also try disabling any 3rd party extensions one by one to see if any are creating issues.
Other than that maybe clear browsing data, cookies etc.
ok thanx tried all above and it turns out clearing browsing data, cookies etc did the trick
I quite often clear from beginning of time which would explain the "randomness" I will try and narrow this down further and pinpoint the exact cause.
Thanx again MW