All versions before 6.31 have this "problem". And it's not really a problem anyhow, depending on how you install. Of course, for the casual user who just installs normally, it acts like a problem, which is why it was changed.
In any case, you can avoid it with older versions of mIRC by installing mIRC to use the install folder rather than the Virtual Store folder by placing a mIRC.ini file into the install folder. Note that in Vista, you will want to set full access to that folder for your login to prevent issues with writing to the folder for logs/downloads/etc. As long as you give full access to the folder, it works the same in Vista as in pre-Vista.
Of course, you could also install mIRC to a location where you already have full access, such as a folder on the desktop, and you'll get the same results.
