@aodoherty The PC tech section is probably the better place for this post, since you're playing in Windows (regardless of how), so I've moved your post. But no one's going to get upset about which Sims section people post in.
The error, if it's accurate, is basically saying that the game tried to reference an invalid memory address. That can happen for any number of reasons, including a corrupt save or a program running alongside the game that's not working as it should. The fact that a new save works fine makes it more likely that the existing save is corrupt, but it's still possible that there's another issue. So please test without Windowed Borderless Gaming or the Steam overlay, still in a clean folder, just to see whether your save loads normally there.
If the save throws the same error, try loading a backup, either one of your own (if you've made any) or the automatic backup the game itself keeps. In the Saves folder, you'll see a folder with the name of your save and a .backup extension on the end. So if your save is Isla Paradiso, the main save folder will be Isla Paradiso.sims3 and the backup will be Isla Paradiso.sims 3.backup. Delete the .backup extension and change the save name (e.g. Isla Paradiso test.sims3), and you'll be able to load that save from the Main Menu.
I posted something about the text issue on the Sims forums, but I'll repeat it here: try editing options.ini to make the game window shorter. The line you want will look something like this:
resolution = 2560 1440 0
If you change the 1440 to something like 1360, still in windowed mode, the issue may disappear. You'll know the window is short enough when you see a bit of space above the Taskbar and below where the game window ends.
The XCPT files in your user data folder are crash logs, probably not useful at all, unless the game happened to run out of memory. But that's unlikely when you're currently loading a save that ran fine the last time you played, unless you happen to have a number of other apps running on your computer at the same time, in which case Sims 3 might not have access to enough RAM. Otherwise, the crash logs don't say anything useful; the error you posted is much more illuminating.
