I admit I'm not super good with computers, so please bear with me if I have actually just made some really silly mistake or I don't immediately provide the right information.
I got my Fate/Stay Night [Realta Nua] through my friend. I didn't have problems with installing the game or running it, and I finished the Fate route without problems. UBW didn't have any problems at first either, but in the beginning of the 10th day when Rin is coming over, the game suddenly shows me an error screen (image in the end of this post).
I use Windows 7 (32 bit) and my applocale is in Japanese. Unfortunately, I'm not sure where my game file is downloaded from. The readme was also added by my friend who gave me brief instructions of what to do. However, the instructions all led to fuwanovels so I would assume the game is also from here.
I have already tried running as an admin, making sure the files are not in read only -mode and have also tried to check my other save files to see if they have problems or if I could access this scene through them instead. I also went throgh different forums in hopes of finding anyone with the same error, but I found none.
Something worth noticing maybe: on the day this problem occurred, I opened my computer to see it had somehow installed norton antivirus on my chrome and also on my desktop, despite the fact I don't even use it anymore (ran out of subscription ages ago).
Changing my applocale back in days had turned my Paint Tool SAI to use dots in stead of Ä and Ö I use to name my layers, but on that day they had changed to actual Japanese markings instead (and have stayed like that ever since). Something has definitely changed but I'm not sure are they actually related to my game problem still. Also, I ran my antivirus but it didn't find anything worth noticing.