Some kind of program is stealing focus from the active window, it's quite strange. I am using Windows 7 Ultimate 64bit.
So for example I open Notepad++ and start typing. After some time (few minutes, sometimes even less), the window loses focus and the program does not receive input anymore. Same with other programs, it's quite annoying.
I already checked for malicious programs. The only change I made to the computer before the problem started occurring is the installation of a new TP-Link USB wireless adapter.
Anybody have an idea?
Best Answer
Because the only change I made in a reasonable time was adding the wireless adapter, I thought the problem should be related to that. I investigated by reverting things I have done step-by-step, first removing the wireless adapter, then closing software that came with it (using the Task Manager).
Turned out it was the TP-Link Wireless Utility.
Got rid of it and it is fine now. It is not necessary for the wireless adapter to function.
@Andrew Thompson reports that one and a half year after I posted this question this problem still has not been fixed by TP-Link.