I've done some more work on this.
It looks like IE 6 has a max query string limit of about 2040 characters. And, IE7 seems to have a similar restriction.
Thus if one has ID fields which are fairly long, such as #0-(4-160840), and one displays 48 rows, then the resulting query string will be greater than 2040 and things in the query string beyond the 2040 do not seem to be accessible to the IE 6 web client.
So, if one wants to use IE with BASE 1.2.5 or 1.2.6, and you have big IDs, then you need to use a lower value for $show_rows - perhaps 42-46 in order to use the Search Results buttons.
Also, with an ID length of 13, such as #0-(4-160840), each row adds an additional 40 bytes to the query string length.
And Firefox does not have this limit.