iligal operation

hi to all…

my PC won’t able to boot windows.i notice that that there was defect with my memory.i change a new one.i made a scandisk i found out that there were a crosslink. and when open the internet explorer it will illegal operation.thats why decide to reinstall it and still the problem occur.

i decide to transfer the hardisk to the good PC and reinstall the OS. i successfully installed the OS, Office and other application. everything going smoothly.
because everything is okey i returned back the hardisk unfortunalely still the problem occured.i made scan with anti-virus but there were no virus.
is it from the motherboard had a problem?

hope u will help me.

john