Thanks for the response.
I had already reinstalled OG when I saw your reply. I subsequently duplicated the problem though.
With a fresh install, I again imported the same csv file and ended with the same result.
The value for column 'client_of_id' for the owner company is in fact 1, not 0, in my database. All the companies, which were successfully imported, are 1.
Instead of closing the window, this time I attempted to log back in using the time out pop up window. I have attached a screenshot of OG showing what happened after I attempted to log in. As happened earlier, I am now unable to access my OG installation (takes me to the "Complete the installation" window).