I'm assuming when you say the little silver box you mean the power window amp. More often than not that is the problem. These parts are always having problems. I had the same thing happen to my s14 and my s13. Nissan wants about $100 for the part, but if you can handle a soldering gun it's a very simple fix. There is actually a write up on 240sx forums.com. Let me see If I can find it. Also if you need any help let me know it's seriously like a ten minute fix.