I had exactly the same thing happen to me a couple of weeks ago, although thankfully my monitors weren't fried in the process.
Do you have a anti-surge powersupply block? It's a 4/6 block connector which allows you to plug all your PC and peripherals into it to ensure that they get a balanced, or at least protected power supply. The theory is that if the mains electricity supply in your neighbourhood is violently switched from one electricity network (grid) to another (particularly common during thunder storms), the electricity going into your house might increase or decrease significantly in voltage (causes your lights to flicker slightly), and this can often cause major damage to your PC equipment.
Well, enough of the physics lesson. I have one of these anti-surge blocks and it has some kind of output dial on it which presumably controls the maximum amount of power going to the PC and the other sockets on the block. I experimented with this and turned it down until it wasn't providing enough power to switch the PC on, and then gradually increased it until the PC worked again. This fixed my problem with getting electric shocks from the L&R analogue outputs.
Or course, like Snoopy4ever says.. it might be just that the grounding on the motherboard isn't working properly, or the power supply inside your PC. I didn't think to check this because turning down the power surge block solved my problem. By the way, if you don't have a power surge block sitting between the mains electricity supply and your PC, I recommend you get one anyway. I don't know how stable your electricity supply is in Italy, but I know a few people in Sweden and in UK who've lost data or equipment from power surges. You can buy them from most PC hardware retailers, although to be honest, this one I have if the first I've seen with a voltage dial.
Sorry it's not for an Italian company, but here's a link to one at an online store.
http://www.jungle.com/webapp/wcs/stores ... 1114644001
<font size=-1>[ This Message was edited by: FlatEric on 2002-05-15 04:39 ]</font>