Anyone can teach me, What is the solution this problem?????????????

Sorry, I did not update my profile. my current auto Cad version is 2015 and my RAM is of 3 gb in operating system of windows 7 32 bits with the processor of  core 2 quad.

I don't have all day to waste.

Try this.  Shut down all non-essential programs running in the background (ex. - antivirus, browser, MS Office type programs such as Word or Excel, etc.).  Next, test the drawing you had the problem with.  Does the problem return?  If it doesn't then continue working.  If it does return close AutoCAD and disable all the bells and whistles that are part of Windows 7.  Test again using the same drawing.  Does the problem return?  If it doesn't then continue working.  If it does then you have to make a couple of changes.

A Win7 32-bit computer can only address, theoretically, at most 4GB of RAM.  It will never fully address all the installed RAM (at best it will address 3.5GB of the 4)  Your system has 3GB.  Upgrade to 4GB.  Next, read the article found in this link to activate the 3GB switch in Win7.

https://knowledge.autodesk.com/support/autocad/troubleshooting/caas/sfdcarticles/sfdcarticles/How-to-enable-a-3GB-switch-on-Windows-Vista-Windows-7-or-Windows-XP-s.html

Now test the result of these changes.  Does the problem return or not?

If it does there is only one other tweak I can think of you could make to your computer and that would be to increase the size of the virtual memory paging file and set the minimum and maximum values to the same setting rather than letting Windows manage it for you.  This tweak will set aside a contiguous portion of your hard drive for paging data in and out of memory and should help speed things up in the process.