aww.. like the begging helps. there is no pity here. only help, if that is what you seek.
when you experience a "dns error"
try to bring up a command tool [start menu > run command > cmd > okay]
and type 'nslookup www.websitethatisfailing.com' without the single quotes
also try to post the output of the above and the 'ipconfig /all' command [in the same window]
this will give us all a bit more to go on
but before try a 'ipconfig /release' followed by an 'ipconfig /renew'
also, when was the last time this machine was rebooted? dns servers could
have changed and you *could* be runnning on only cached addresses..