All files seem very normal.
It appears that you have updated Yahoo! Messenger at some point (judging from the file names "performance_build_0" and "performance_build_2162")
And with that update came a few more log files (eg: "client_iuliana"), that's all.
The example text of one of the logs you put in your post simply tells you that, at one point, Yahoo! Messenger tried to connect to your email ("MAPILogonEx failed") but failed for some reason, eg: bad connection.
Nothing out of the ordinary.
More detailed info can probably be found at one of the official Yahoo! Messenger-sites:
Yahoo! Messenger: Help
Yahoo! Messenger: Tutorials
Yahoo! Answers: Messenger
Yahoo! Groups: Messenger
etc...
Remember, this is a forum about Messenger Plus!, an addon for Windows Live Messenger, which is a completely different IM program.
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