Starting 8/24/04 somewhere around <10% of the visitors to my site try to GET the url http- modemsite.com/56k/1

I can't figure this out! They all seem to be MSIE (6) browsers on all versions of Windows.
For example, a visitor clicks on a Google results link to a page on my site that, other than ad codes for Tribal & GoogleAdSense, loads only 2 gifs & the html. A couple seconds later, request is made for the 56k/1. (modemsite.com/56k/chipset.asp)
In all cases, the GET from client for the 56k/1 doesn't include a referrer, but does include the session cookie.

Any ideas what's going on?
Sample of ALL log entries for 1 IP from 9/04 log showing
Date, Time, GET, URL, Querystring, User Agent, Referrer:

9/1/2004 7:12:02 219.95.232.xx GET /56k/chipset.asp - Mozilla/4.0+(compatible;+MSIE+6.0;+Windows+NT+5.1) - http://www.google.com/search?hl=en&l...ork+once+win95

9/1/2004 7:12:02 219.95.232.xx GET /56k/IMAGES/logo_top.gif - Mozilla/4.0+(compatible;+MSIE+6.0;+Windows+NT+5.1) ASPSESSIONIDCSQTQBTC=FNGBDIHCPKDFKLODJOEGJIGJ http://www.modemsite.com/56k/chipset.asp

9/1/2004 7:12:03 219.95.232.xx GET /56k/IMAGES/logo_bottom.gif - Mozilla/4.0+(compatible;+MSIE+6.0;+Windows+NT+5.1) ASPSESSIONIDCSQTQBTC=FNGBDIHCPKDFKLODJOEGJIGJ http://www.modemsite.com/56k/chipset.asp

9/1/2004 7:12:06 219.95.232.xx GET /404.asp 404;http://www.modemsite.com/56k/1 Mozilla/4.0+(compatible;+MSIE+6.0;+Windows+NT+5.1) ASPSESSIONIDCSQTQBTC=FNGBDIHCPKDFKLODJOEGJIGJ -