I had this crazy Windows 7 issue going on last night. Well it may be because of Windows 7. I run a 64 bit version. Anyway what was happening is files I had in a folder for a certain game which were seasons for a baseball game were having their timestamps changed. However that was not all. When I added a different season to the folder it would not show up. So the time stamp changed on files already in the folder and the new file was not added. I deleted the seasons with the new time stamp because I did not know what to think of them anymore. Now the company I bought them from replaced them but this is just strange. I ended up creating a folder just for the season I had yet to download and put them in a separate folder so nothing would be erased and nothing was. What is going on here?
Sounds like to me someone is remotely controlling your computer and is messing with your files.
Do these files require a special program to open? If not what do you use to open the file? How was the time changing time was it showing earlier, current system time, forwards in time? What time was changing creation time, last write time, or last access time? If it is last access time it could be antivirus scanning the file. The antivirus many times access the file to check things like file headers and for strings when it comes for signature base. And for sandboxing test they will load the file into memory. Or it could be a really poorly written file infecting virus that does not get the last write date and last accessed date of the file. Then use the SetFileTime function to set the file dates back to the originals not sure if they deprecated the function for windows 8+ haven't tried. Always thought that it was a really weird function call in the windows api made the audit history for any given file useless for a for forensics.
In regards to the file types they are RAR files. Also I didn't use anything to open them. I was just copying and pasting them into the folders. The funny thing though and I don't think I mentioned this already but it would not let me drag the RAR files into the folders like I was able to do before. Something really strange is going on here. I really don't know what it is.