Okay, Charliee. I am back again. I just put in the old Samsung 512MB stick in the second memory slot and i booted the computer and I am using the computer now. No problems. I do not have to change anything.
I just run again CRUCIAL memory scan. this is the result:
1024 MB DDR PC2-5200 512 MB DDR PC2-3200 Maximum Memory Capacity: 1048576 MB
Currently Installed Memory: 1536 MB
Available Memory Slots: N.A.
Number of Banks: 2
Dual Channel Support: N.A.
CPU Manufacturer: GenuineIntel
CPU Family: Intel® Pentium® 4 CPU 3.06GHz Model 4, Stepping 9
CPU Speed: 3065 MHz
Therefore, as far as the results by CRUCIAL memory scanner, it is incorrect that the memory stick in firts slot is DDR PC2 5200. As it specified on the stick, it is DDR2 PC2-4200.
Hope this can help you. The orientation of the second stick is different than the first one, in my case, in that, the side of stick with those square chips on it face AWAY from each other, make sure you do not damage your sticks trying pushing in.