Thanks, but I have no mods added,and never did have...and yes,I've uninstalled and reinstalled already,both on Vista and XP SP3[which I assure you it does affect,although I've not tried the mentioned fix on that at the moment as I uninstalled it when I put it on the Vista machine],using the same files for both.
I have followed the instructions exactly.
From that I'm beginning to wonder if the expansion pack downloaded correctly,although I've not seen it cause any problems in-game except for the Esc problem,so I would think that is unlikely,but possible,but I don't want to pay for another download.
Looks like I might have to run it without the expansion pack added,which makes it a bit pointless buying it,unless anyone can think of anything else to help.