Firstly ,Welocme to BBB Mus,
For your problem you can check this post https://bigblueball.com/forums/yahoo-messenger-support/37890-yahoo-messenger-illegal-operation.html which will help you
Hope you will be happy with that.

The hard disk internal structure consist of 2 things:-
1. The file allocation table
2. The actual data
FAT contains the pointer to all the location where tha data stores,that linked with each other.
If the file is deleted from the specific location the location will be empty but the FAT contain the link to that location and it is easy to recover that file from location.
So,there is 2 way to delete the file permanently(that can’t recover using any s/w) is-:
1.Fill that location of HDD from which the data is deleted by adding some kind of data(u can say it as a rewrite but actually its not).
2.Just format the FAT.

After formatting the FAT nobody can recover the data using s/w,but still there is a mechanism for recovery using h/w that is known by the HDD desingners according to the structure of particular company HDD.

This error message is often caused by the incompatibility between Windows Blinds and Yahoo! Messenger, but is not limited to just that program. Windows Blinds has a support forum filled with Yahoo! Messenger & Windows Blinds compatibility questions that you should check out asap to resolve this issue, there does appear to be easy fixes…

1.right click on yahoo icon go to properties, then compatibility, then check disable visual themes.
Fix your yahoo – A Forum Post by hysteriadis
2.This issue appears to be a problem with any program that alters the original skin / shape / form of Yahoo! Messenger. One have the exact same issue with XNeat, below is an example of “skin” change caused by running XNeat, that impacts on the operation of Yahoo! Messenger….
https://bigblueball.com/forums/attachment.php?attachmentid=963&stc=1&d=1158980964
clicking the Close / Exit button in an active IM session window will immediately cause Yahoo! Messenger to crash and display “Yahoo! Messenger has encountered a problem and needs to close….”
If you encounter any problems that cause Yahoo! Messenger to crash unexpectedly or that you can reproduce, quickly run through your installed programs to see if they alter the default look and feel of Yahoo! Messenger in any way.
If Yahoo! Messenger is crashing when you load it, make sure you have Macromedia Flash Player installed, this MUST be installed via Internet Explorer.

According to me,yahoo chat help is better than others room.There are many bots but lesser than other rooms.Otherwise as scorp said,”The only good yahoo chat room where one doesn’t run into a lot of hassles and fights of one kind or another is a “conference” room with invited friends.”. is better way.The room written by dermot is also gr8 too visit and really there is a lesser number of bots,but i did find bots there too.