Assuming anyone is still following this thread...
In a random act of desperation i resorted to google for the error messages i was getting.
And i found this (amongst all the usual guff) that may be a clue...
Possible Mod_security block I'm not sure i have the ability to modify this from my cpanel access on my server so i was going to raise a support ticket with my hosting company to see what they think.
Anyone think it might have mileage in it?
