I have only one user who has this problem.
She is on Excel 2007 on Win XP (1024/768 monitor resolution, 15 inch monitor)
Each time she opens and closes the Sort dialog box, the dialog box gets bigger when reopened.
This means that by the 3rd or 4th time she opens it, it is so large that she cannot get to the edges of the dialog box to make it smaller.
Odd that this only happens with only the sort dialog box... ..