I found this out this morning after doing some research. As we all know, when in Safe Mode, you are limited to 640x480 screen resolution which makes things a PITA to get dialog boxes to work correctly.
Give this fix a shot ans see if it works for you.
Right click on your desktop.
Click Properties.
Click the Settings tab.
Under Screen Resolution, drag the pointer to the right (where higher resolutions are located). Do not click OK . Just move the slider to the resolution that you want.
Click the Advanced button.
On the new window click OK, without modifying anything to close that window.
Click OK to get out of the next window.
Done, you should have successfully changed the resolution settings.