I am using avast internet security 5 my system spec are -
1- intel core 2 duo e7500 2.93 GHz
2- 2 gb ddr2 ram
3- windows xp professional 32 bit sp-3
4- nvidia geforce gt240 1gb ddr3
after installation of avast everything goes fine but when i open my computer system freezes for 5-6 sec but mouse moves
with same spec in (windows 7 ultimate 32 bit) everything works fine.
please help me 
On your XP-P machine (#1 machine), how many things do you have running at Start Up? Are there any items that are unnecessary that you can āDisableā (not delete)?
When you say that your machine āfreezesā for 5 - 6 seconds, are things loading up at this time?
You can also always go to the Avast GU > Settings > Troubleshooting > click on āload Avast services only after loading other system servicesā to see if this helps.