Thanks for the help, got the site offline (it's not 
vBulletin itself, but a site using its software).  

However, the offline browsing is extremely slow.  I 
check the source, there are scripts including banner 
ads, popup windows and a webtrend live tracking ...  I 
think browser is waiting for these scripts timeout.

Is it possible to get rid of these script?  I tried no 
external page, no error page, bring all the backgroud 
image offline, detect/nodetect links in script and 
truned of browser script.  Still not quite satisfing, 
unless everyting is out and leave a plain text file.

Any ideas?