Monitor: change color, blinking, too old

I have a 7-yr old 16-in monitor (KDS: Visual Sensation). It was fine until several days ago when it began to change color by itself (to pink) and started to blink or flick or blur.

I have changed the properties from ‘true color’ to ‘256 colors’. No solution.

Checked the cable connection, no loose cable (just rudementary check though, not sure if it’s enough).

Questions:

1. Is this sign of virus? If so, what is the most likely culprit? (Have scan the computer with Norton AV with latest LiveUpdate (4/26), no virus found)

2. Any hardware problem? Cable all the sudden broken? Video card? How do I check as a lay person?

3. Or it’s just a sign of good old monitor. Nothing I can do beside shell in the money to buy a newer one?

Thanks