Go to C:/program files(x86)/Adobe/Captivate/AdobeCaptivate.ini (For Windows 7)
C:/Program Files/Adobe/Adobe Captivate 6 x64 (for Win 7 with Captivate 64 bit)
C:/program files/Adobe/Captivate/AdobeCaptivate.ini (For Windows XP)
Open the file with notepad.
you need to write this "Use32BitJVMForPublish = 1" (Without double codes) in AdobeCaptivate.ini file.
Note : Make sure Adobe Captivate is not running while editing .ini file.
Save it and Try to publish the project.
Thanks.