Thanks for your input!
Well, no, files are not automatically decrypted when you log in to Windows. However, if you are sharing a PC with a single account, then it’s simply not a very suitable environment to keep any kind of secrets.
Is it really a requirement to share the same account? It’s such a bad idea in so many ways…
Also, using different passwords for different files is seldom an optimal strategy. I wrote a blog post that discusses this, http://www.axcrypt.net/blog/use-of-different-passwords/ .