Hi lately i had a weird problem in CAD .i was using CAD 2012 for years and it was fine . then someone send me a newer version of CAD 2014 and i was forced to install it .it was fine for 2 or 3 days then one time i couldnt use any ribbons with click  .it means that i can use commands , although autocad crashes after a while and the top ribbon fades .i uninstalled with every program you name and installed back to 2012 version , i did a lot of things but nothing works , every version of cad has the same problem . i even erase the traces in programdata folder and registry but didnt work . so help me , i am out options .

Are you saying you followed the uninstall procedure as recommended by AutoDesk then reinstalled 2012 and the problem still persists?

Hi and thank you for reply .yes i Did uninstalled exactly as Autodesk said and the problem exist .sometimes it crashes and want to send an error report too .it is an unexpected error .

What are your system specs?When you reinstalled did you disable your anti-virus program?  Did you also disable the UAC?

Of course i did . i DID tell that i had AutoCAD 2012 and it worked for years . i didnt have any problem . now all Autocad programs crash . 

Then it sounds like a problem with the Windows Registry.  Wipe the drive and start all over.