Try disabling all background running applications. Click START | RUN | type MSCONFIG press OK. Place a dot next to Selective startup and then remove the checks from AUTOEXEC.BAT and CONFIG.SYS. Next click the STARTUP tab and uncheck each item on the list (except for system tray), press OK and restart the system. See if the issue returns. If it does not, then you can replace one check at a time, restarting the computer after each to test if it is the culprit.