This happened all of a sudden without I doing anything special. I can only cut and get that dotted line display, but as soon as I move the cursor to another cell the dotted line becomes solid again and I can't copy and paste.
At the same time as this happened with Excel something very peculiar happened with internet: the connection to my Gmail account and to Experts Exchange was completely interrupted whereas other websites worked fine. At first, it displayed No internet access in the status field in my Windows 7, then it displayed normal but still the connection to my Gmail account and my Experts Exchange account was completely down. (Other accounts like my Hotmail account worked though.)
I am in Thailand now, and I know they are gradually implementing their own version of The Great Firewall of China. Can it have anything to do with that?
Now about 10 minutes later I can access my Gmail account and my Experts Exchange account again.
I've lived in Thailand in the same place for about 2 years, but for about the past half year internet is behaving much differently than earlier, very unpredictable.
However, I need to get my Excel back to working condition again. What should I do so that I can copy and paste again, and undo and redo?