You need to check which version of UFT you are using. If it is older than 2.8, you need to go to the UFT web page http://www.uftree.com/UFT/Nav/ufttech.htmlhttp://www.uftree.com/UFT/Nav/ufttech.html and get the upgrade to version 2.8.
If you are using version 3.0 you need to upgrade to 3.1. Both of these upgrades are free. You can not upgrade from 2.x to 3.x for free.
This should solve you browser problem. I suspect your version is older than 2.8 or you would not be having the browser problem in the first place.
By the way the replacement of the motherboard should not have affected your UFT program on the disk. You might have a downloaded copy of an upgrade still on the disk shich you can just install over the one you reinstalled.
After you finish the upgrade you might want to run "Utility - Project - Check" and/or Utility - Project - Check - Repair" and the "FIXME.BAT" program located in the UFT main folder.