finding core dumps in public root Am suddenly finding lots of core..xxx files dumped in the root of my site.
In devMode cant see any issues. Assume this is serious issue and memory dump?

Where to start? Logs have loads of stuff but nothing that gives me a clue to this.
Those aren't Craft log files.  I'd suggest contact your host and give them the files so they can look and see what's dumping them and what the root problem is.