Problem in migrating Phpbb forums to Kunena forum

Hi All,
I have successfully migrated from phpbb3 forums to kunena 1.7 using kunena importer. Everything is working fine but my clients started complaining that they are not able to login using their login credentials that they used in phpbb3. But i am able to view the user list registered in kunena user manager. Plz give solution to this issue… I am totally strucked, my forum got over 8000 users and it’s impossible to ask them reset the passwords. Is there any solution for this. Please help me out!!

Joomla version: 2.5.4
Kunena: 1.7.2

If you manually installed it that would most likely fix it. A google a will show you how. The phpbb forum guys will not even help you untill you’ve tried that measure.