You haven't said what operating system you are using.
If it works in safe mode but not in normal mode, it just means that the monitor you have connected is not capable of working at the resolution/refresh rate that you had previously set.
In XP you can change the video settings by right-clicking the screen and choosing "Properties". Then go to the Settings tab and adjust the resolution slider to match that specified for your monitor. Then click the Advanced button, go to the monitor tab and set the refresh rate (for LCD monitors this is usually 60Hz).