Many thanks for your reply Holger1405, I've attached the file.
Just to give a little more info; when I emigrated years ago I brought over an external drive with a copy of most of my data including my Mass Effect folder (installed from CD) which contained a HD texture mod.
I copied it over to my current machine and it still worked perfectly dispite being in a portable form. I played this for a while a few years back and only recently became excited about getting back into it again.
Since my last post I have now downloaded and installed the game via Origin on a separate drive and attempted to load my saves but this still didn't work. I've tried the original solution of moving the Save and Config files several times now but it always crashes in the same way. Even my very very old saves no longer work and I have backups of those so it's not that they've spontaneously corrupted.
Creating a new character will let the game actually load in although I haven't yet tried making and loading an entirely new save, I'll have to try that after work.
I wondered about Claymix's suggestion of the game not liking multiple installations but I assume that is only relevant with Origin, and I've never before installed it on this PC via that client.
Thank you so much for your time.
Edit:
Well I figured it out and it was actually very easy! After testing the newly created save from a fresh career, which worked correctly, I had a hunch to try loading my old save from within the game itself and this was the solution. For some reason it loaded perfectly and I was able to create a new save which loads every time.
My old original installation still crashes when trying to load the new save, perhaps if I were to create a new career from within this installation it would salvage the save in the same way, but I'm content with the fresh installation with the latest texture mod.
Thank you all the same! Hopefully this will help someone in the future.