Help. PC Tools Anti-Virus v5 bogs down computer

Running a clean install of WinXP with SP3 (all updates included) on an older [P3] machine with 1.0 GB Ram at 1.2 GHz clock-speed.

Installed the following security apps:
Comodo BO Clean
SuperAntiSpywarePRO
Malwarebytes Anti-Malware
PC Tools AntiVirus v5
ZoneAlarm Free


Prior to installing PC Tools Anti-Virus v5, I had v4 installed and that worked for a few days until I received an "Error 104" message during boot-up, so I uninstalled v4 and installed v5 instead.

After v5 completed installing, the computer bogged down and essentially would not react to the mouse or keyboard. Tried re-booting several times and received the same effect. Thus, had to reboot in safe mode to uninstall. Currently have Avast Pro (as a Trial) installed.


Here's my question(s):
1) Has anyone else experienced a similar problem with PC Tools Anti-Virus v5 (or v4 for that matter)? If so, how did you solve the issue?
2) What recommendations can you give for a (free) AV program that INCLUDES email scanning and real-time protection (preferred). I realize that email scanning may not be needed, but I'd rather be safe than sorry. I use both Outlook and Outlook Express for emails.


Thanks for your help.

 

Had my reply all typed out and submitted it. Either I got timed-out on the Forum (???) or it got lost in cyberspace. Anyhoo.... here's the condensed version:

Apparently do have real-time protection enabled for SAS and Malwarebytes.

Will follow your suggestions about security apps.

Going to uninstall Avast Pro and SAS, using Revo Unistaller -- GREAT app!
http://majorgeeks.com/Revo_Uninstaller_d5706.html

Avira Personal Edition Free does not appear to offer email scanning -- you need the Premium and above for that.
http://www.free-av.com/en/download/1/download_avira_antivir_personal__free_antivirus.html

As far as I can tell, AVG Anti-Virus 8 Free does not explicitly state it scans emails for virus / spyware, but as you mentioned, I also believe that it does.
http://www.avg.com/product-avg-anti-virus-free-edition#tba1



Even though ZoneAlarm is heavier on resources, I like it because of ease of use. However, if Comodo Personal Firewall offers greater protection, and is lighter on resources, than I'll give it a try.



On a side note, what are your thoughts on Dynamic Security Agent (DSA). It's not available on MajorGeeks, but can be found here:
http://www.privacyware.com/dynamic_security_agent.html

Is this an add-to (other security software) or an instead-of?



Thanks again for our help!

 

Sorry, forgot to mention that I'll be trying AVG Free... and that my question regarding Dynamic Security Agent (DSA) is for informational purposes only.