What do u mean by "wager dll"?
A wager is a bet, He's betting that your issues are caused by a DLL, Did what I suggested above fix your issue? I know quite a few users have had crashes without riched32.
You're suggestion that it happens when a certain amount of users joins a channel makes me wonder if this is a external issue, such as a DLL.
Anyhow, Post your issue over on the WineHQ thread and see if anyone else has the same issues.
Do you have the same issues with a clean install of mIRC?