Head unit gone bad???

Hello all,
I have an 87 Saab 900 s which I bought used about two months ago and I absolutely love my car. One (and only one) problem so far: there is "something wrong" with the head unit (I'm guessing)... I will be playing the radio or a cassette and suddenly the sound stops (and the cassette stops), and the LCD display goes completely blank within a few seconds. Then it will come back on and play and within a couple seconds it does this again. Some days it does this all the time, some days it doesn't come back on unless i hit it (probably not good), and some days it is just fine and I have no problems...
I was thinking maybe there is a loose wire or something? Or maybe the head unit is just bad and I should replace it?
I have no idea about cars and I am a BROKE college student so maybe someone can tell me what they think could be wrong? Has this happened to anyone else?

sounds like you have a poor connection in the back of the radio. it could also be something inside the radio itself. the stock radios were not very reliable to begin with. you need a special tool to get the radio out. go to a saab dealer or a european auto shop and see if they will let you borrow their radio removal tool. check the wires behind the radio. sometimes aftermarket radios were installed and then taken out and the wires were cut and spliced. these connections can sometimes come loose. this may not be the case with your car, but i have seen it a lot. make sure the little fuse in the back of the radio is in tight also. if all the wires look good, you will need a new radio. stock ones are very hard to come by and you will most likely have to get an aftermarket one.
do you have a rear amplifier in your car? i have seen these go bad and intermittently knock out sound to the rear speakers. the amp only powers the rear speakers if you have one. if you dont have a rear amp. it is definitely wiring or radio. the amp is located under the rear seat on the right hand side of the car. lift back the carpeet and you should be able to see it under the metal brace. good luck.