Lots of possibilities, but my first guess is a video card compatibility problem, even though it works on another system.
I had a similar problem years ago with a Diamond Stealth 64 card, system booted okay, but the screen was blank (I could type in the shutdown keystrokes and the system would then shut down correctly). Plugged in a Rage card and everything was fine.
Did a quick search on the Epox website on "blank screen" and came up with the following:
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''Diamond Speedstar A90 AGP locks with blank screen after driver install ''
Location: Technical Bulletin
Article #: 1204
Product: EP-3VBM
Operating System: Windows 98, Windows 98SE
ISSUE
Diamond Speedstar A90 AGP locks with blank screen after driver install.
SOLUTION
Update the Diamond Speedstar A90 AGP graphics card BIOS to version 2.25E4807 or newer.
The update is available on the Diamond website.
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Do you have any other video cards that you could try? If not, are there some familiar keystrokes (i.e. shutdown) for your Windows version that you can type in to see if your system reacts?