snn5-fw.n-bone.net

Hello,
In the last few days my computer seems to have had some problems.
When I start up and sign into the internet a popup comes up saying they
are unable to verify the identity of snn5-fw.n-bone.net as a trusted
site. possible reasons include being connected to a site pretending to
be snn5-fw.n-bone.net, to obtain confidential information.
my homepage was google so I don't know what happened.
But I did virus scans, ad aware scans, downloaded other programs to
scan my computer yet still nothing comes up.
Now when I try and access google it gives me the message 'We're
sorry...... but your query looks similar to automated requests from a
computer virus or spyware application.'
I've tried everything I can think of but it's not worked.
I'm sure there must be something on my computer doing this and I don't
want my information to be stolen!

Can anybody help me?
Thank you,
Sam

sam