By default when you click a web link in an internet aware program and there is already an Internet Explorer window open, the web page appears in the open browser window instead of opening a new window.

This trick prevents the new link from being displayed in the existing IE window by forcing an additional IE browser instance to open.

You must make the following changes to the Windows registry.

CAUTION: We strongly recommend that you back up the registry before you make any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify only the keys that are specified. Read the document How to make a backup of the Windows registry for instructions.

Click on START > RUN and type regedit
Then click on Ok button.

The Registry Editor, will be appeared.
In the left pane of the Registry Editor, navigate to the following subkey (making double click on each registry key):

HKEY_CURRENT_USER
Software
Microsoft
Internet Explorer
Main

Now, in the right pane of the Registry Editor locate and make double click on the following registry subkey named AllowWindowReuse

If not, make it. In this case, in the right pane of the Registry Editor, right click in the white space and choose NEW > DWORD Value to create a new subkey.
Name it AllowWindowReuse
Now, make double click on it.

A new window will be appeared.
Modify the value in the field named Value data.
Set the value for this subkey to:
0 (read ZERO) = Don't Reuse Window
1 (read ONE) = Reuse Window

Then click on Ok button.

Exit the Registry Editor.

Restart the computer.