I'm not sure if this question belongs in this forum or not because I'm not sure what is causing it. If I have internet explorer (with several tabs) open and also Outlook the computer will randomly switch to EITHER another open tab or back to Outlook while I'm working. It happens also if I am working on a Word Document. I'm not sure where to start LOOKING for the problem. I assume you are using XP? as this issue normally affects that...

1.
Hace you turned on speech recognition, but not configured it? I which CASE you just need to disable or configure it correctly, see the microsoft support link below.

Programs May Start, Quit, Lose, and Gain Focus Randomly
http://support.microsoft.com/default.aspx?scid=kb;en-us;313176&Product=winxp

2.
PowerToys for Windows XP is a free utility from Microsoft which give you addition power and control for tweaking XP, you could use that to prevent switching (as another option):
http://www.microsoft.com/windowsxp/downloads/powertoys/xppowertoys.mspx

Install TweakUI
Start it up and go to: General > Focus > and check the "Prevent applications from stealing focus" box.

3.
As a final option - there is a tweak fix is from kellys-korner-xp to Prevent Programs from Stealing Focus and comes with an Undo:
http://www.kellys-korner-xp.com/xp_tweaks.htm

Line 66. (r-h column) Prevent Programs from Stealing Focus - Undo
To use the VBS Files: Download .vbs file and save it to your hard drive (you may want to right click and use Save Target As). DOUBLE click the vbs file. You will be prompted when the script is done.


NOTE any scripts/registry editing can be dangerous, so always check what it is entering first (open with notepad and read them yourself if needed), these are labeled pretty safe and come with undo incase. I suggest trying the Microsoft options first as they would be a safer option. It's also better to work out why and resolve the problem, rather than just patch the issue. Hopefully it's just the speech recognition issue.

Did this just start? If so, your first step is to run a full malware scan with BOTH your anti virus utility AND MalwareBytes. Frequent focus changes are often the work of Malware.I just completed "turning off text" and I will see how it works. Thank you!