I am using Windows XP version 2002 SP 2
as i start computer a dialog box with title "Can't run 16-bit Windows program" opens in desktop and where "Insufficient memory to run this application. Quit one or more Windows application and then try again" is written. there is only OK to click. once i click OK then it never appears until i start again. Why it appears though i was not running any program. and it appears only once.

Is your computer running antivirus program ? Is it up-to-date?

Check here to see if there is a program that will start on bootup:
C:\Documents and Settings\All Users\Start Menu\Programs\Startup

Also similar directory, but with your user name instead of "All Users".

Be a part of the DaniWeb community

We're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.