what's the reason cad dwg make a fatal error..i used autocad 2007 liscence1)  ?????2) ??????

There are many reason can cause fatal error. 1. Does it happen only to one file or all files?2. If only one file has the problem, what happened if you open it on other computer?3. What is your computer spec?*I think I sound like JC now :)

Hello, it's important for you to know on what command this happens --> then you do and extended zoom + SAVE your file before you try that command again.
There are also various possibilities when a fatal error happens :
1 - You can save your file anyway.
2 - You can't save your file.
If you can't save your file you've got 3 options :
Re-open the same file ( you have lost may be 15 minutes of work, check your variable : SAVETIME in minutes ).
Try to find, rename and use your XXXXXXX.sv$ file if it's newer than your XXXX.dwg OR XXXXX.bak.
Is your file too big for your computer ?
Please let us know if and how you have fixed or not the problem.

Some fatal errors are memory related.Some fatal errors are a result of a conflict between two programs or processes.Some fatal errors can be caused by your anti-virus program.What exactly were you doing or attempting to do when you got the fatal error?What is the exact wording of the error message you are seeing?  Post it here.AutoCAD 2007?  Have all updates been installed?  Have all applicable hot fixes been installed?What OS are you running and what version of the OS?  Example: Windows XP Pro SP3If you are having the problem with one particular drawing have you tried to open it then run an Audit on the drawing?