I rewrote the Question to add everything that i tried so far.

• Many of my applications are being opened by Internet Explorer. (not all)

• For example when I run Firefox.exe (from shortcut) I get IE run instead, with the following URL

  http: // %22d/ Browser/firefox.exe%22 (I added spaces to prevent link creation)

  1. the shortcut target is: "D:\Browser\firefox.exe"

  2. when I attempted to open firefox.exe from it's folder the results were the same as the previous one

  3. I attempted to open it by cmd, so i navigated with cmd to the FF path then wrote: firefox.exe

  4. the was the same except that the URL was:

     http: // Firefox.exe/

  5. when i jsut write firefox the result URL was:

  http: // Firefox/ (is it some kind of parameter or something??)

  1. trying the same with chrome resulted the same results as the previous tests.

  2. I tried creating a new user (adminstartor) but the problem still there.

  3. I tried every registry key with exe on it (not sure if i tried them all) no change

  4. I tried removing IE but came back by itself somehow, meanwhile IE is removed, FF and its fellow apps gave me open with window

  5. I tried reinstalling the applications but it just no use.

Time Line: (as requested from @Daredev)

1. I don't know when it happened because the computer is for the company i work for and it was like that since i got it. (The IT there gave up on the problem lon time ago!).

2. applications were installed already are "firefox" and "XPS viewer" .

3. applications were working after the problem everything except what uses browsing (MS help viewer, XPS viewer, firefox-even I've re installed it-, opera, chrome)

4. that what I thought but after installing Maxthon , comodoDragon this theory was blown away.

system info:
1- windows xp professional service pack 3
2- system fully patched: Yes
3- anti-virus up to date: Yes
4- same behavior when booting into safe mode: Yes