There is a sudden problem for the operation of many functions. 
Only very basic functions work such as draw a line, insert a not, etc
"Export to pdf", "line extension", "edit annotation", "Edit Block Attribute", and etc does not work at all.

example 1
"Export" -> "pdf export" : This should make a pdf file, but the Draftsight does not do anything.

example 2
type "EX"-> enter key -> enter key : This should extend an existing line to the next end, but does not do anything.

example 3
double click on annotation or block : this should open a dialog box, so I can edit the annotation or block, but does not do anything.