Spyware blocking pages

Hi,
I have a few computors on my network. I have come to notice that we cannot view some websites while for other we see the opening page but cannot go to any links. The browser just stops after getting the header ( i viewed the source file and i can see only the header downloaded).

I am assuming this is a spyware as there is one comp. that we do not usually open and we can view the pages with this comp. with out any problem.

I have used all spyware software to remove any spyware on the pc's but this problem still exists.

Has any one faced this problem and how do i get rid of this spyware. I also use firefox which does the same with these pages or websites.

thanks,