We use linkwall to block websites, but it now stop access to various wesites that shouldn't apparently be blocked

The linkwall log file shows, for example
08/Jul/2008:10:32:02 +0000] "GET Google HTTP/1.0" 403 0

The linkwall.lst file is

Connectotel LinkWall Test Page

$include sys:\blacklists\adult\urls
$include sys:\blacklists\adult\domains

$include sys:\blacklists\aggressive\urls
$include sys:\blacklists\aggressive\domains

$include sys:\blacklists\dialers\urls
$include sys:\blacklists\dialers\domains

$include sys:\blacklists\drugs\urls
$include sys:\blacklists\drugs\domains

$include sys:\blacklists\games\urls
$include sys:\blacklists\games\domains

$include sys:\blacklists\gambling\urls
$include sys:\blacklists\gambling\domains

$include sys:\blacklists\hacking\urls
$include sys:\blacklists\hacking\domains

$include sys:\blacklists\onlinegames\urls
$include sys:\blacklists\onlinegames\domains

$include sys:\blacklists\phishing\urls
$include sys:\blacklists\phishing\domains

$include sys:\blacklists\porn\urls
$include sys:\blacklists\porn\domains

$include sys:\blacklists\proxy\urls
$include sys:\blacklists\proxy\domains

$include sys:\blacklists\sexuality\urls
$include sys:\blacklists\sexuality\domains

$include sys:\blacklists\violence\urls
$include sys:\blacklists\violence\domains

$include sys:\blacklists\weapons\urls
$include sys:\blacklists\weapons\domains

$include sys:\blacklists\warez\urls
$include sys:\blacklists\warez\domains

$include sys:\blacklists\whitelist\urls
$include sys:\blacklists\whitelist\domains

I did look up Google in the urlblacklists.com and it does show up in a long url in the adult category. However we are also seeing blocks on mail.yahoo.com as below. This shows up in the mail and webmail urlbacklists but as you can see we do not use those.
[08/Jul/2008:10:23:48 +0000] "GET http://mail.yahoo.com/ HTTP/1.0" 403 0

Any ideas?

Thanks

Kerry