Use the Windows Task Scheduler to run your browser’s executable
firefox.exe with the hyperlink of the webpage
http://superuser.com as the parameter.
You don’t want to run a file, you want to run the executable. For you its probably
"C:Program FilesMozilla Firefoxfirefox.exe" http://superuser.com. Copy and paste that into the run box. If it opens
superuser.com in Firefox, that is what you want to put into the task scheduler.
You can use the Windows Task Scheduler to do this, as its built right into XP.
To open Scheduled Tasks, click Start, click All Programs, point to
Accessories, point to System Tools, and then click Scheduled Tasks.
Navigate through this, setting up a description for what it will do, a title, etc. When it gets to choosing a program, make sure your action is going straight to the Firefox executable. By default that is c:Program FilesMozilla Firefoxfirefox.exe (on XP).
Adding a URL in the parameters using “http://url.com” will do it. Specifically for Stack Overflow, use this as your command:
c:Program FilesMozilla Firefoxfirefox.exe
If that did not work, you could also put it into a batch script, and have it kill Firefox after X time, although that is beyond my personal knowledge.