'OK' button disabled in Config/Add custom Extension dialg window-w

[Rich]

I am in IIS on my local computer (winXP SP3). I am trying to add a custom
extention to the Default Web configuration tab. I go to Home Directory
tab/Configuration button, and I click the "Add" button which brings up the
custom Extension adding dialog window. I browse for aspnet_isapi.dll. I
have a few versions -- one for framework 1.14 and one for framework 2.0+. I
add my custom extension -- .xyz ( or just xyz). But the "OK" button
is/remains disabled. I tried the same thing on our server (win2003) and the
"OK" button is enabled in the "Add Extension" dialog window. I tried both
versions of aspnet_isapi.dll on my local workstation with no luck.

Here is a little history on my local computer. I used to have full admin
rights, but after a virus attack -- the IT guy reduced me to a power user
after spending a week clearing out all traces of the malicious software. The
power user level wasn't working out for me, so he restored me back to full
admin on this workstation (and on the network). We restarted the
workstation afterwards, but still the "OK" button in the "Add Extension"
dialog window remains disabled.

Is this a permission thing? Or is it something else? Maybe something got
tweaked in the Registry that I need to fix? Any suggestions appreciated.

Thanks,
Rich