-Fast and reliable messaging
-Your contacts presence updates e.g. Available or Offline, in virtual real-time
-The ability to customize your own status messages e.g. Back in 5 mins, On the Phone
-Complete access to your existing Yahoo! Messenger contact list
-The ability to invite multiple users into one conversation
-The ability to make it your own with avatars, emoticons and custom ringtone alerts
How 2 reinstall yahoo messenger :
1 - visit:www.blackberry.com/yahoomessenger.
2 - select ur language..3.n then download it.
btw I 2 had the same prob.when I got 2 fix it, thought that I should let u guys know it 2.hope it works 4 u
Download Yahoo Messenger