The HARD way, though perhaps more 'scientific' that doesnt require so much tabbing in and out... Log off your Character. Open EQUI_BuffWindow.xml, find the X & Y size of the window, and then open up UI_<CHARACTER>_<SERVER>.ini, find Height and Width for your UI (and resolution) for [BuffWindow]--if the lines dont exist you will need to create them.
example:
Code:
Width=45
Height=900
Width1280x1024=45
Height1280x1024=900
Width1024x768=45
Height1024x768=900
That SHOULD do it.