Periodic Internet Explorer Web Pages Advertisements Appear withouut my doing a thing

I have a problem that keeps occurring on my Win98 2nd Ed PC that I need some
help clearing up.
Every morning, 3 Internet Explorer windows appear on my screen.
They are the same each day. The Explorer windows contains no address bar,
tool bars or menu bar. One of them is advertising a "screen saver" list
that I supposedly one can preview or download them free of charge. One of
them is a commercial ad to purchase AOL. And one of them is a large black
screen containing white text as follows:
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Privacy Protection Aleart [Version 3.5-BC5]]
C:\BrowserCleanser\Update\Privacy_Protection
IMPORTANT: Your computer may be recording your Internet Activities withyout
your knowledge....etc.
Would you like to see ehat has been recorded on your computer? [Y/N}[ Y
Click the "OK" button and begin your Privacy Protection Update [RECOMMEDED]
C:\BrowserCleanser\Update\
C Windows and DOS is a Copyright of Microsoft Corp 1985-2001.
BrowserCleanser is not affiltiated with Microsoft Corp
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Every day the exact same windows appear and sometimes they appear again
during the day....!

I presume that I somehjow, accidently downloaded something or visited some
web site that caused some program to be placed on my PC and it automatically
runs.
PLEASE, Someone tell me how I can get rid of these happenings....!
Carl Ward