I think I have discovered a serious security bug in Windows 8.1. Today I was using my (non-Admin) user account and with Internet Explorer I saved a file in the default Downloads folder (under This PC). The file was saved, but when I went to that folder, the file was not there! Now, I was about to download it again, using IE, same as before, when I noticed in the Save dialog box that the file had indeed been downloaded, and that it was there, in the Downloads folder under This PC. Frustrated, I went to that very folder, but the file was nowhere to be found. I was really puzzled. Then, by chance, while logged in another account (namely the Admin account), I happened to go to the Downloads folder, and there was the file that I had downloaded using the other account. Obviously, what I described above represents a security problem: firstly because my private files may get saved by mistake into another person's account without me even realizing it, and secondly because I was able to access another person account (i.e. the Admin account) via the IE's Save dialog box, seeing the list of the files there, and possibly even accessing them (I have not tried the latter, though). Has anyone experienced anything like the situation I described? I must also say that I later tried to replicate this abnormal behavior, but for some unknown reason I couldn't.