@casiepa I was able to delete some posts from a date range.. so may be its possible but I have not tried it myself.
@johnjamesjacoby Thank you for your support.. I did what you suggested but But whenever I corrected some of the characters I would go about 10 topics further and it would stop again. I also tried to delete some records altogether. But no improvements then. However, As a last try I have installed the bbpress in test folder on the live server and started the import process from the live Database. So far I have imported all the users (~17,500), forums (~30), topics (~225000) and running on ~350000th reply in the last 2 days. I am not sure how it worked. But the same DB export did not work on my local instance. However, I have to bear with the time it takes on the live server.
On the side lines if this import completes Do I have to invite all the users to re-register in the forum ?
Yes, I have all the php.ini variables very high. timeouts to 48hrs and Max sizes to 2GB.
It does not stop at a particular time but at a particular record.