ASUS P5B-VM Series---Please help

[nyaxinya]

i have the ASUS P5B-VM Series with 3GB of RAM running at 2.75GB. the processor is a Pentium(R) D with 3.21GHz running at 3.20GHz.....i recently reinstalled Win XP after having problems with the previous Win XP i had installed....the problem was that when i open a page either internet explorer or windows explorer and if i wanted to scroll it would act as if the machine was kind of like freezing. Now that i have reinstalled the OS i still am experiencing the same problem....what can be the problem....please help