Windows Vista machine with screwed up IE

I bought a new machine with Vista Home Premium loaded
Since I had no Internet access at the time, I assumed Explorer
was refusing to startup because no network was detected.
Anyway I am now connected to a cable set top box via a
fixed ethernet cable and I have a wireless networking capability
with my old WinXP machine working properly via wireless shared
Internet connection.
Vista Explorer tries to start but I am told it is failing because it is
trying
to get through the Welcome sequence. If I try to write a web address
it refuses but can sometimes got to msn. Once there I can break out a new
tab and get to Google.
Setting default programs is screwed, because it does not see Eudora
and whatever I choose, it is never remembered.
I tried starting the Welcome sequence from the file, and this gets me
all the way through until I press the exit arrow.
Here it displays a page error and will not exit until I close Explorer.
Also Windows Mail fails to start because it suggests my anti
Virus is using it which is untrue.
I tried altering the Home page but this will not work. It always
goes to the startup sequence.HTTP://runonce.msn.com/runonce2.aspx
and the Tab header says "Customise your settings" with a blank
blue screen below.
Will I have to reload Vista completely?
It's not registered yet. I have an "External recovery disc"(32bit) from the
manufacturer. If I used this, would I get into more difficulties?
Would it wipe out my network settings? ( I paid someone to set it up)

Thanks for any suggestions
Perry