How come one of our computers could not get inside Google or
MSN.Search's websites and is instead automatically routed to Plesk
website? Has my browser been
highjacked? How do I remedy the situation? Thanks

The fact is that computer is infect whit a spyware, the way to remove
those is to go to download.com and look for a litle tool call adaware,
boot the comp in safe mode and run adaware , its prety simple to run
its an anti-virus look like program !

Good Luck !

As himselff said your browser is infected with a spyware and well, you
couldu use Ad-Aware to solve this, but it really doesn't remove every
spyware, so if it doesn't work you could and well, should download the
"Microsoft Anti-Spyware (beta)" released few weeks ago, you can find
it here:
It's good program and it has removed alots of spyware on my computer.
But the third choice and maybe the best is to download the program
"Spybot - Search and destroy" which i've used for year, it has built
in "Internet Explorer resident" preventing websites installing spyware
to your computer, if i'm not wrong "Microsoft Anti-Spyware" also has
this option, but Adaware doesn't.

Of those three I would recommend Microsoft Anti-Spyware, my experience
of that program is very good, but Spybot search and destroy also.
Just remember to update the programs using the "update" features.

Adaware SE Personal download link:
http://www.lavasoft.com/software/adaware/
Microsoft Anti-Spyware download link:
http://www.microsoft.com/downloads/details.aspx?FamilyID=321cd7a2-6a57-4c57-a8bd-dbf62eda9671&displaylang=en
Spybot, search and destroy download link:
http://www.safer-networking.org/en/download/index.html

Hope this helps you :)

I have seen this problem many times before.  You will find a
comprehensive list of spyware removal tools (AdAware, Spybot Search &
Destroy, Microsoft Anti-Spy, HiJackThis etc...) <a
href="http://www.vermontpcsolutions.com/tools_spyware.html">here</a>. 
I recommend running AdAware, Spybot, and Microsoft Anti-Spy. 
HiJackThis is for advanced users and should be used with caution.  In
my experience running all three of the mentioned programs will catch
and remove most spyware.  You can also find a list of resources
(forums, articles etc...) pertaining to removing spyware <a
href="http://www.vermontpcsolutions.com/res_spyware.html"> here</a>. 
I hope this helps.  Good luck!!