The View Logs dialog was removed in mIRC v7.1 for two reasons: I often received comments about its non-intuitive design, and I often received emails from users who had trouble finding the folder where their log files were stored, since they wanted to access them directly.

The new behaviour gives you access to your log files directly through the Windows explorer interface. You can also search through your logs using the Windows explorer search feature by right-clicking on the folder name and selecting "Search".