When sorting a range of cells with the RAND() function that contain random numbers, those cells may appear not to sort correctly. In fact, the cells do sort correctly. However, after the cells are sorted, the spreadsheet recalculates a new set of random numbers, which will be unsorted.
To sort random numbers, first turn Auto Calc off in the Calculate menu, then Sort.
If you manually recalculate, the entire range of random number cells will be recalculated, resulting in a new set of unsorted numbers. To retain the original random numbers, you can copy them, then Paste Special to an adjacent blank column/row of cells.