Have you tried:
– deactivating all plugins to see if this resolves the problem? If this works, re-activate the plugins one by one until you find the problematic plugin(s).
– switching to the default theme to rule out any theme-specific problems?
– resetting the plugins folder by FTP or phpMyAdmin? Sometimes, an apparently inactive plugin can still cause problems.
Many thanks esmi but unfortunately this has not worked – I have deleted all the plugins for good measure and I am using he default theme. I may have to resort to a fresh install. Thank you for your help anyway
Have re-installed wordpress again and getting the same error – I give up 🙁
FOLLOW UP: After a quick consultation with my wonderful hosting service I was advised that all I needed to do was to generate a .htaccess file with the code: SecFilterEngine Off which then goes in to the httpdocs of the domain or subdomain.
This switches off the mod_security and now wordpress is working full throttle!