VISTA - target=_self does not work?

Our intranet home includes a simple html page which has a simple list
of who is in the office. This simple list has a refresh button, which
uses target=_self. Intranet home page also includes a "traffic" bar
which has an image at the bottom that links to the sponsor of that
traffic info.

I am setting up Vista SP1 Dell workstations in my office, and have 2
stations that behave different despite being identical. Station one
has been set up for 2 weeks. Station two is IDENTICAL hw/sw but only
set up a few days, fwiw. Both are "up to date" per windows update
site.

Station #1 opens our intranet home page, but if you click the refresh
button in our who-is-here list, it opens a new window or tab, ignoring
the TARGET=_SELF. ??? In addition, the traffic image link pops open in
a new window or tab. In addition, Station #1 will not open mapped
drive html files, just UNC. I can live with unc, but I mention it as
possibly related.

Station #2 has none of these issues, and behaves just like an XP
station. Both users are in the same domain with same rights.

On #1, I have messed repeatedly with IE7 settings under Tools-
>Options, and reset back to default, and continually reloading,
restarting and testing. NOTHING MAKES ANY DIFFERENCE (argh). Station
2 has no problems, just like all our XP sp2/sp3 stations.

Ideas??

Matt