If the link is coded to open a dialog window (usually a smaller sized window or one without the usual menu/toolbars), then it doesn't get diverted to a new tab. But most should be fine (e.g., Google or Bing search results). If those don't open in a new tab, hmmm, something is broken. (I suggest closing and restarting Firefox and then testing.)

thanks for the reply. somehow it has resolved itself, but it wasn't dialog windows, it was just normal links, which i wanted to open in new tab for convenience.

Start Firefox in Use Troubleshoot Mode in Firefox to check if one of the extensions is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.com/kb/Safe+Mode

If it does work in Safe-mode then disable all extensions and then try to find which is causing it by enabling one at a time until the problem reappears.

• Use "Disable all add-ons" on the Safe mode start window to disable all extensions.
• Close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

In Firefox 4 you can use one of these to start in Safe mode:

• Help > Restart with Add-ons Disabled
• Hold down the Shift key while double clicking the Firefox desktop shortcut (Windows)

• https://support.mozilla.com/kb/Troubleshooting+extensions+and+themes

I have the same problem. But the problem was corrected after I run CCleaner and fix all registry issues.

Restart firefox... Fixed

I had this problem too. Inspired by cor-el's suggestion, I just disabled Tab Mix Plus 0.4.0, and the problem went away.

What is a little weird about it is that for me, all new tabs opened in the same windows. I could have several windows open, but every new tab opened in just one window, and always the same one.