Try starting Portal with Admin rights (Right click -> Run as Administrator). It seems like it wants to update, but does not have enough rights to release open files or overwrite updated files.
In this case the program loads the updated file, tries to update - fails - closes - start again - tries to update - fails - closes - start again and so on.
Sometime its shows a Terminate Button but i am not fast enough to read.
Create a screenshot using the print button and paste the screensot to paint or so