Hi.
 
This problem is in my work PC only, Not home PC.
Sonar keeps freezing when I'm composing my music and I don't know the condition really.
 
Is there a .log file in the folder of Sonar somewhere to send you?

Sonar creates minidumps when it crashes, which you could send to Cakewalk support. Don't know how long it will take for them to respond ...
 
The other option is to provide more detail in terms of what you are using (hardware, what is used in your Sonar projects, ...) and have the forumites help you get it sorted.

if your using Windows 10 then it may possibly be related to this problem that cakewalk is already aware of:
http://forum.cakewalk.com/Instability-with-certain-Cakewalk-plugins-after-recent-Windows-10-updates-m3526221.aspx
 
As Rob said, provide more details. The more info you leave the better off you are to solve your problems.