Acer x153w monitor frequently says no signal

i bout my x153 acer monitor last december 2008. about four months after that i noticed some vertical fuzzy stripes throughout, though you have to really look at it to notice. now it makes another weird thing. whenever it wants to, it displays NO SIGNAL and turns black. When i reboot, it goes fine, but there are times it goes black again at once. 
i can't take it back to the store at this time.
can somebody help tell me what might be causing this?
thanks