I presume by "reset" you mean you have re-installed windows
(again i presume windows xp) - many default features of windows
xp can cause problems - ie the default power saving feature is
set to spin down the hard drive - this can cause a stall - also
a default setting is to put the pc into hibernation mode after a
short period of time - another event that can trigger a stall
another very important issue is to make sure you re-install
any motherboard specific drivers that came with the pc -
things like pci and agp bridge drivers - also dma and ide
bus drivers as these items can easily cause a stall or crash
etc if not installed properly