I did run the disk utility and nothing changes. Also, there is no difference if I login as root or as a different user. I also tried the chsk command at console startup. Then I optimized the entire system
What I'm now thinking is that some of the shareware applications I downloaded, tested and discarded may have missed up some sort of file type list maintained by the system. Is there any? Is so, where I find it? I am anyway going to report the thing to Apple. But, strangely enough, I don't have any another misbehavior on my Mac, which I'm using extensively,