Despite of the Yshania's luck, my computer is still refusing to work properly.
Minerva's comment: "I want to cry...
Okay, I went through Troubleshooting process via Safe Mode, and started with config.sys, autoexec.bat etc to identify if there's any particular line causing my computer problem.
I found "Image" programme was the cause to start Windows, so I removed it. (I knew that programme is up to no good. I should have removed it long time ago.
Now, I can start Windows, though I bypassed all start up programmes by using Msconfig, just in case.
However, when I tried to do something, ie. save a document onto a floopy, it goes to the blue screen with "fatal error" message, then the screen froze (I could still use mouse, though). I used Alt+Ctlr+Del to check which programme was causing the problem, and found it's "Explorer". Of course, if I "end the task", whole screen went blank.
Also, sometimes it didn't freeze the screen and went back to the main windows screen. But I got "active desktop error", even after I turned off the background. The background had gone white with the message and icons. Very bizzare...
I suspect the original problem was caused by Image, trying to create image while Windows was doing something else, then broke both.
The Win98 Troubleshooting suggested to "reinstall Windows", but without any mention of "back up" or "reformat". Is it possible to reinstall it over the current system? As I mentioned above, I cannot send any files to anywhere, thus I cannot save anything onto my CD-RW. If I can reinstall windows, then save files I want to keep, I will reformat the whole hard drive, and reinstall windows (again) etc.
Sorry, I know it's confusing, because I'm confused...