computer locks up

After changing harddrives and reloading windows my computer still continues to lock up on a regular basis. A few other strange things are happening, examples= When loading aol 7.0 or 8.0 it says that its installing 6.0 but locks up at the 97% done everytime. I have a 96 meg memory chip but it reads out at 88 meg during the power on sequence and in the device manager window. The computer can work fine for a little while then just locks up for no paticluar reason. I have to cold boot after it locks up.