So here I'm. Joined to post this fix because I know a lot of people are experiencing the same problem as I'm. My solution was to launch the game in windowed mode. To do so, access the propeties of your ut3 shortcut. Now you should see a line with something like this "C:\Program Files\Unreal Tournament 3\Binaries\UT3.exe". Now to set the launch option, simply put "-windowed" without the "" at the end of the line. This should launch the game in windowed mode.
Example:
"C:\Program Files\Unreal Tournament 3\Binaries\UT3.exe" -windowed
Hope this helps!
Example:
"C:\Program Files\Unreal Tournament 3\Binaries\UT3.exe" -windowed
Hope this helps!