Are you hooking the monitor with the 15-Pin, or the DVI?
Also, what model is the monitor?
a year ago i bought a acer pc with a new samsung Monitor, but i got a problem since the start. when i start the pc my screen will turn black and in the left upper corner ther appear a text that showing digital, analog, digital ,analog. that takes about 5 or 6 times than the screen turns black. the monitor is still on because my power indicater is going on/off/on/off.When i got the pc i managed it to get it on the digital mode and worked fine,I had to this for 2 weeks and then the problem disaperd. But now i got my old problem back but different now is that i cant get it on digital mode anymore, I tryd everything. used both cables, installed drivers and looked at my settings but the only way i can use it, is in analog mode but i cant play games on this mode.
Hope someone can help me ...