If you have an older color graphics adapter, redrawing the screen may cause display interference colloquially called ``snow''. The display interference shows up as white streaks on the display. Press PgDn and PgUp to test for display interference.
If display interference appears, reset the videoMode option of Point. To do this, position the mouse cursor on the word OTHERS on the top line of the screen. While holding down the left mouse button, move the mouse so that the line videoMode = 0 is highlighted, (it is the bottom item on the menu) and then release the button. The bottom line of the screen will prompt for a new value. Type 2 and press the Enter key.
Try PgDn and PgUp again. If interference still appears on the left side of the screen, you can eliminate it by repeating the above procedure but giving videoMode a value of 3. The value 3 will cause screen updating to be slower than when the value is 2. If there is no video snow at all, leave videoMode at 0 since this will provide the fastest screen updating.