Computer shutting down on its own

My computer will randomly turn itself off. The frequency has increased to 30 mins or so from the time of going on the internet.

I am not sure if this is relevent but the CPU usage is at 100% almost all of the time while I am on the Internet. at (46 processes and 1 application)

I specified this happens when I am on the internet because when it is not connected to the internet it doesn't shut itself off.

This was given to me and was a home built computer.

I have minimum ram at only 512mb. But that shouldn't affect just the internet usage.

My computer Information:
Windows XP Home
Service Pack 3
2.4 GZ Intel Celeron
512 RAM

Recenlty Installed Programs:
ZoneAlarm (I did not have an Active Firewall for awhile)
Avast
Marlware Bytes
A-squared

I am really getting frustrated with this prblem and would really appreciate any help that you could give me.

 

have you scan your system with malware bytes?

 

Hi jewelianne, are you on Broadband or 56K Modem when you connect to the internet? When did this start happening? Try removing the Programs you installed one at a time to see if that is the cause. I run Avast and wouldn't remove that. You may have a clash with Zone Alarms or A- squared. Neil.

 

Yes I did run Malware bytes and one thing came up It said ADWARE MY Web site. I did notice that it started after I installed A-squared. I lost my desktop and now have an error sign always on my desktop and it won't recover. I also lost that after installing a-squared. I will uninstall it. I have broadband connection. Does the CPU usage have anything to do with it since it runs so high only on the internet?

 

Thank you all for your help. I am going to except the invitation to the Malware and Virus Removal. Thank you all again.