Vista boot issue or dying hardware?

[zero002021]

I use a Dell Dimension C521 at work, and recently it started giving me weird issues upon boot. For example, the screen will sometimes flash multiple colors (blue, green, gray and red) instead of showing the standard windows loading bar. Normally, the system would boot fine after flashing the colors, but today it didn't boot, and the only way to get it to do so was to disconnect and reconnect power.

I've tried doing a few searches online but haven't been successful in finding any information. I was hoping someone here might have experienced this before or know how I can resolve it. More specifically, is the issue OS (Windows Vista) or hardware related?

And before anyone asks, I'm the only user on this computer, and I ran a virus scan which came up clean.