Hi chaps and thanks for the continuing advice much appreciated.
I'm installing to my "D" drive and also not to the Program Files\ folder. I've checked the paths that the game updates want to install to carefully as well.
I can re-install the game and fire it up but that's about it. My previous installation before stopped working after patching to v580, it also contained both of the DLCs which installed just fine first time around as well as the 577 update which worked by copying the 577 files from a temp folder into the game folder.
My new installation works and if I copy the 577 files in to the game folder it still works BUT if I do the same with the 580 files either with or without 577, then the game no longer launches. Also if I try and install either of the DLCs by selecting the appropriate addpack via update screen nothing happens and they don't install it never even tries to install them, that's how I left it last night after three new game re-installs and several re-downloads of relevant patches etc..
The irony is that I never actually play the game but I just wanted to keep up to date with patches and maybe fire it up to look at new features when and if time permits.