Same problem is described Here but that thread is locked and I cannot find any solution there so I need to start a new thread, I have totally same problems that roundhead face, , any body can help?and how I can tag a member I want to call Mr. vladimir michl who answer on that threadThanks in advance.

Can you replace the ACAD.cui(x) and/or ACAD.MNL from a backup copy? Either these files or a XML parser in Windows are probably damaged.

thank you, I need to call IT persons of my company for this purpose, after that I can tell you wither it is use full or not. 
thinker2013-09-09 08:57:29

AutoCAD keeps a back up copy of the CUI in one of its many folders.  It actually carries the name...acad.backup.cui

For these files I use windows search and get hereC:\Autodesk\AutoCAD_2010_English_Win_32bit_SLD\x86\acad\en-us\Acad\Program Files\Root\UserDataCache\Supportbut no backup files.
thinker2013-09-10 15:43:07

Sorry, my mistake.  It's actually acad.bak.cuix you are looking for.  I checked on my system. 
John Connor2013-09-10 18:25:48

[QUOTE=Vladimir Michl] Can you replace the ACAD.cui(x) and/or ACAD.MNL from a backup copy? Either these files or a XML parser in Windows are probably damaged.[/QUOTE]Thank you for your reply, 1st two files I replace and now CAD file can open in less time but other problems remain same how do I search and replace 3rd file?

Find and read the MS Knowledge Base article #324460 entitled "How to install Microsoft XML Parser...".