ST4 crashes on exit

[DarkStar]

Hello lovelysidhu and welcome to the forum.

I am sorry to hear about the problems you are running into.

-- has the ST4 plug-in ever been OK?
-- VSTi or VST3i edition?
-- any error messages, dump summaries?
-- does the ST4 standalone program crash on exit?

As this is primarily a user to user forum, someone-else may chime in. Meanwhile, the best thing to do is raise a Support Ticket, here:
http://www.ikmultimedia.com/contact-support/mi/
for some one to one help (US (East Coast) Business hours, generally). But they will want details.

[Peter_IK]

Also make sure you're running the latest update (including sound updaters) from your IK User Area under "My Products"