After upgrading from 4.7 to 4.8 only problems,pls help

[13mirex13]

1  PC rebooted on boot process (I find the problem-disabling Zone Alarm on startup fix this ,   
    I don`t like this)
2  3-5 aps dint started correctly on startup (some error mesages,not related to Avast;service not started,memory can`t read)
3  30-50% Moore CPU usage
 I uninstall-reinstall-nothing better
 finally ,back to v 4.7 solve problems
 easy

WIN XP SP 3,
Avast over one year on PC with no  big problems
sorry for my English
Thanks for help

[rassel]

Try to update your avast to 4.8 again. If the problem still happen to you again reply back if no reply back too.

[Lisandro]

Do you use a firewall? Which one?
Do you have any other antivirus installed in your system?  Did you have in the past?
Any other security programs that could interfere?
In XP/Vista, is there any useful information into Control Panel > Administrative Tools > Events, specially 'Errors'?