Cad failed to open prompting ways to do missing ac1st16.dll.txt

　　 1. http://toothchill33.mystrikingly.com/blog/ on my laptop or computer ------ properties ------ sophisticated system settings --- environment variables;

　　 two. Add an 'Autocad' method variable, the variable worth is: C:\\ProgramFiles(x86)\\CommonFiles;

3. Modify there . there ​​are: SystemRoot%\\system32;%SystemRoot%;%SystemRoot%\\System32\\Wbem;%SYSTEMROOT%\\System32\\WindowsPowerShell\\v1.0\\;C:\\ProgramFiles(x86)\\MicrosoftSQLServer\\ 100\\Tools\\Binn\\;C:\\ProgramFiles(x86)\\MicrosoftSQLServer\\100\\DTS\\Binn\\;C:\\ProgramFiles(x86)\\CommonFiles\\AutodeskShared\\

　　 4. The modification is successful, without having restarting the computer, straight open the CAD, achievement!