Expert advice needed!!!

Hi everyone!

I'm new to the site and having bizarre problems with my laptop. I've got a Dell studio 1537 model PP33L

If I try to go online I get a scary message saying "Cannot connect to the real www.google.co.uk" as something is "interfering with your secure connection" and it is "returning unusual and incorrect credentials". I've tried running a scan and its not detecting any viruses at all, which is weird as it usually detects loads.

So I've decided to completely restore my laptop back to factory settings and start over. I've had look at the help settings on my laptop which says to press F8 as my computer starts up but there is no F8 option, this does nothing, there is no F8 option, only F2 or F12.

I'm at a complete loss with this, I've tried reading loads of forums they all say to go for the F8 option. If anyone could shed any light on what's wrong with my laptop or how I can fix the issue I'd be really grateful :). My datas all backed up and I'm ready to go.. I just don't know what to blooming do!

Thanks :)
Serena