How to suppress the auto reboot with .iss file ?
.iss file will have the information about what ever the actions your installation does during the recording process(creation of .iss file) of that particular application.
Check in .iss file is there an item called BootOption.
Set the value for this to 0 (BootOption=0)
If the system goes for reboot automatically, then the value of BootOption in the .ISS file will be 3. Inorder to suppress this we need to put the value of BootOption as 0.