檢查電源設定, 有沒有休眠設定,
還有monitor是設定為 auto detect 還是現用的型號

還有一件事，　關掉所有 screen saver

關掉屏幕保謢程式,
為的是要將原因找來;
因屏幕保護程式可能
與視窗的節能管理有關。
而導致監視器誤以為
電腦己關機,
而自動關掉監視器。
找出原因後可重開屏幕保護程式

那麼你的問題解決了沒有?

無乜頭緒,
試下直接進入MONITOR的設定看一看,
即直接按MONITOR上面的MENU.
看看有沒有Energy Saving 的東西，
最後看一看連接到Monitor 的線有沒有鬆，
開蓋檢查PCI 槽，Display Card 有沒有鬆.

不如換個keyboard試下....可能個keyboard壞左都唔定

It is very strange that your keyboard turns off monitor.
As I mention before, you may have some screen saver or energy saving program
running, that use some specify keys to switch on.
Sometimes it is not a direct screen saver program but a clock program or picture program will have this features.
Some freewares have bugs that lock up the screen rather go into screen saver mode.

Using the Control Panel to check any quick key function is assigned to the CTRL key

using notebook??
some combination of keys will switch off screen

WHEN YOU START THE COMPUTER HOLD DOWN THE <DEL> KEY AND ENTER THE CMOS SETUP, LOAD THE DEFAULT CMOS SETTING AND TRY AGAIN.

IF IT DOESN'T WORK, UNPLUG THE COMPUTER, REMOVE ALL THE INTERFACE CARDS, IDE CABLES, SATA IDE CABLE, USB DEVICE(S), KEYBOARD AND MOUSE, AND REINSERT THE VIDEO CARD, KEYBOARD AND MOUSE ONLY, THEN TRY AGAIN.

IF STILL HAVE NO LUCK, YOU SHALL THINK OF GETTING A NEW COMPUTER.

1. TRY TO ISOLATE THE PROBLEM.

I FORGOT TO LIST 1.4 AND 1.5 IN PREVIOUS POST

1.4 CHECK THE COOLING FANS' CONDITIONS, INCLUDING THE ONE IN THE PSU.

1.5 REINSTALL WINDOWS WITH MINIMUM REQUIRED DEVICE, HARD DISK, CD, KEYBOARD, MOUSE , VIDEO CARD, MONITOR.

2. IF YOUR COMPUTER HAS SERIOUS HARDWARE PROBLEM, YOU SHOULD NOT BE ABLE TO COMPLETE THE WINDOWS INSTALLATION.

3. CHECK THE RAM STICKS, CHECK FOR ANY SWELLING CAPACITOR AROUND THE CPU.

4. THE WORST CASE IS TO HAVE A NEW COMPUTER.

應該不是了...
~~~

Bring it back and ask for a reason. 如果想 diy, 就去 msconfig disable 曬d startup applications.