A new owner, you say ? Could it be some pre-installed trial programs or
crapware ? You might have to 'de-gunk your PC '
(http://www.winvistaclub.com/e19.html)in that case. I suggest you use
PC-DeCrapifier and additionally run a 3rd party anti-spyware too. Spybot
or a-squared are good freeware.

Your computer is pretty likely infected with malware. No Google software
behaves this way - browser hijackers do.

Run thorough malware checks with your anti-virus and anti-spyware programs.
Consider posting in  the Vista security newsgroup if you still need help
after that.

microsoft.public.windows.vista.security:
http://www.microsoft.com/communities/newsgroups/list/en-us/default.aspx?dg=micro
soft.public.windows.vista.security

Charlie42

Google certainly doesn't behave the way you describe, so you may have
inadvertently downloaded some malware/spyware. Try running Windows Defender
from the Vista start menu. Alternatively download Malwarebytes Anti Malware
(wwww.malwarebytes.org) and run that too.

It is possible that your home page has been hijacked but that requires more
specialist knowledge. You need to run an application called 'Hijackthis' to
create a file of what is going on on your PC. The file needs then to be
looked at by a Hijackthis expert. There are newsgroups available that can do
this for you, but you will have to give them time to analyse the contents of
the file.