The problem I have is that the system will not enter the GUI interface unless it's being bootlogged

You need to provide some more details. What exactly happens when not having the bootlog activated? Does it start into DOS then? If so, it may just have BootGUI=0 set in the msdos.sys.

No, it seems to enter the GUI, but then hangs on a black screen. I don't know why.

I've also tried to read the bootlog when I do activate it, but it seems to be overwritten every time the computer starts up.
(i.e. Choose "Normal"? Yeah, it's there that time. Choose "Command Prompt Only" when you restart? The bootlog is overwritten with the Command Prompt Boot steps.)

Ok, It doesn't seem to be ONLY bootlogged.

It takes a few startups to make it work. I don't know if that means a capacitor is not working properly. (i.e. the capacitor has to warm up in order to work properly)

Ok, I think it works correctly now. I think I know what was the problem...

After I had repaired my motherboard (I replaced the USB ports and PS/2 Mouse+Keyboard ports), I also took off a capacitor that didn't seem to want to go back on. (Don't worry, no real damage was done. The leads seemed to have been clipped incorrectly.) So I replaced it with one with the same capacitance, but a higher voltage.
The only problem, it was sitting in my hot garage's electronic parts box for a while, and I think it was reforming itself every time I turned on the computer.