I know a few people who have experienced this too. It seems to me that this has occured more often in recent years though... maybe due to some change(s) in mIRC 7.x, or even in Windows 7 compared to XP.
Maybe it would be helpful if mIRC created regular (weekly) backups of the main settings file, like browsers do for bookmarks and such.
E.g. create an mirc.ini.bak file, then a week later, replace it with a new one... or even keep the last 3 or so backups.
That way users experiencing this issue could easily go back to a recent version of their settings, rather than having to redo everything.
