Originally Posted by aiharkness
Yep, it's a common issue. If I've ever read the solution, I've forgotten.
I'm assuming Yahoo is supported in the country where your carrier is located. Is that true? No blocking or interference with the service by the carrier, either by carrier's policy or government regulation? (I know you've said where you are, but I don't recall it at the moment.)
Have you tried logging into yahoo on a computer, then logging out, and then trying again to log in on the BlackBerry?
No restriction for YM here. It works flawless on any other phone. I have tried everything. Changed my password to "all letters" (some say it works for them like this), logging out from my PC and others. No change in issue.