My computer keeps telling me I have a critical system error and when I click the yellow bubble on the toolbar it comes up with a certain companies software download page. How do I get rid of it?evene though I have Google as my deffault web page it redirect me to companies "ALERT" page..

As previously mentioned:

Here's some ideas for you.
To make sure everything is running fine run both anti virus and anti spyware apps in normal AND safe modes. (make sure that they are updated first ! ;)) (AVG (http://free.grisoft.com/doc/1) is good and free AV)
(A couple of good removal tools are Spybot (http://www.safer-networking.org/) and Adaware (http://www.lavasoftusa.com/software/adaware/))

ALso an on line virus and spyware scanner is Trend Housecall (http://housecall.trendmicro.com/)

Just a note; actively running two AV's on one machine can cause problems.
So if you are thinking about it make sure your current one is disabled first.
SAme thing applies to online scanners as well.

If this doesn't work can you please let us know more of the symptons and your computers setup.

I am scanning my notebook using trend micro house.. and it has detected 1 TROJAN and 18 cokies... now it is removed some of them but could not remove TROJAN

I was trying to delete if from system32 but it says access denied

The above mentioned scanners are best run in Safe Mode

Now how to get rid of the TROJAN any suggetion?