OK. Found errors in Event Log showing as:-
Faulting application httpd.exe, version 2.2.15.0, time stamp 0x4b8fed95, faulting module php5ts.dll, version 5.2.13.13, time stamp 0x4b853813, exception code 0xc00000fd, fault offset 0x001519ef, process id 0xee8, application start time...