Some servers respond with wrong IP address for my domain

[Mickey Mullin]

We're a small company who hosts our own DNS and email.

When I first set up our DNS server over a month ago, I had mistakenly
entered the wrong IP address for the primary nameserver (things not to
do at 2:30am...).  I corrected the problem by the end of the next day,
but it seems that a number of DNS servers are still returning the old
information!

The domain is websoft.com.  The addresses that are affected are
mail.websoft.com and vermont.websoft.com (mail is an alias for
vermont).

Our registrar is Network Solutions (now VeriSign, I suppose).  Our record
there correctly indicates our nameservers and
their IPs:

http://www.netsol.com/cgi-bin/whois/whois?STRING=websoft.com&SearchType=do
-->
VERMONT.WEBSOFT.COM	65.166.221.131
NEWJERSEY.WEBSOFT.COM	63.149.85.239


And a query of our own nameserver returns the correct answer:
dig @65.166.221.131 mail.websoft.com
-->
mail.websoft.com.       1D IN CNAME     vermont.websoft.com.
vermont.websoft.com.    1D IN A         65.166.221.131

But a simple lookup on a web interface returns the incorrect address
from way long ago:
http://www.bankes.com/nslookup.htm (mail.websoft.com)
-->
63 . 149 . 85 . 131 mail.andrews-art-gallery.com

I know there are other DNS servers returning wrong information,
because we are failing to receive email from people.  For example, I
created an account at email.com and tried to send myself, but I do not
receive messages to my account.

Our DNS record is now correct and the TTL passed many eons ago.  What am I
doing wrong?  What can I do to bring things back into place?

Thanks in advance,
Mickey Mullin