ENLARGED text only on boot-up

System is running 98SE, PentiumIII 500MHz. Cable modem connecting to internet so Client for Mocrosoft Networks is running. Only at boot-up does the display show enlarged text of “ENTER NETW” letters ae about 3″high and colors are distorted. Normal screen display should read “Enter Network Password”. At which time hitting the Enter key will bring up the desktop. From this point on, all display functions are normal. What controls this screen? I upgaded from 98 to 98Se and also check for any viruses. I have not yet tried un-installing and re-installing the network options/functions.