I've tried the "recover" drawing and insert the affected drawing into a new drawing but it still giving me the same error massage - "Drawing file is not valid"
 
I've had format my hdd due to automatic reboot problems (as advice by our I.T. personnel) and reinstall my AutoCAD2005 and this massage occur since then. I'm using Windows XP sp2 before the crash.
 
However, I manage to open certain file which is an old acad file.
 
Currently running on windows xp sp1 and I've done check & re-checking on the folder & file security/sharing option - still unable to open the drawings.
 
Really appreciate if anyone can help me on this.
 
TQ.Carlade2010-11-19 05:07:40

This is just a message informing you about a new file format, not supported by your AutoCAD version. User Autodesk DWG TrueView to convert the DWG file to your version.
 
See also:
http://www.cadforum.cz/cadforum_en/qaID.asp?tip=2869
 

Thanks for the suggestion and I,ve done not only that but this too:-
 
-Upgrade my windows XP to SP3 (windows Update Website)
-Installing TrueView 2008 and Used it - (Same Error Message)
-Installing DWG TrueConvert 2007 and Used it - (File Error)
-Installing Design Review 2011 - Not working because I'm unable to update visual C++ 2008 SP1.
 
Well, thats leave me one last option = Buy and upgrade my AutoCad 2005 versions.
 
Question is... all the drawings that I'm unable to open WAS created with Autocad 2005 which the same version,same Installation CD being Re-install in my P.C. and the program is running as normal. I can do my work and open old drawing files.
It Just that when I wanted to open the recent project drawings it gave me that error. (The Whole Particular Project Drawings)
I did ask my college to open the drawings which used the same version, (diff. Installaton CD) - The same error message.
 
 
 

The error message means that your DWG file has an unrecognizable file format. This means that either it comes from a new version (just install the DWG TrueView 2011 as the tip advises, the other tools are not needed), or that the file is damaged (disk controller error, virus attack, etc.).

Yup. Done that too... = "Drawings file could not be read"
Now it seems like the problem is not related to AutoCad.
 
I've back up the files(*.dwg) using Nero Software and restore it after the hd being formatted.
 
I guess something wrong Nero...not the AutoCad.
 
By the way thanks for the advise, I do appreciate it.