Still having problems. Don't know how to solve this.

Dear Sir,
I had no problems with CNET but when I got this new PC, Windows 7, every time the TechTraker says I have new updates, every time I try, it says "no registered application for this extension". This is using my normal browser Opera. When I copy and paste the address to Internet Explorer, no problem but why does it give me this problem and I would much prefer to do it on Opera.
Beforehand I had Windows XP. Always I use Opera.