No fuses blown? To me it sounds like a classic short circuit where the power wire of a circuit has come in contact with ground. This can also happen when an assembly (such as a radio) develops an internal short, but this is fairly rare, so I'd suspect that there's a bad power connection. Because you've sort of indicated that there was no blown fuse, I'm suspecting that the radio or some other accessory has been added by a previous owner that modified the circuit so that it worked without a fuse or was fused in the wrong place - this is dangerous, you could start a fire.
To find the problem, you can either learn to diagnose electrical problems yourself or pay a lot of cash to have a garage do it for you. To do it yourself, you should get the following: a wiring diagram for the car, a multi-meter, and the basic tools to take the center console off.
For a start, I would take the console off and have a close look at all the connectors and the wiring harness in general - you may might get lucky & see where it was/is shorting. If not, you'll need to determine if the radio or any other component in that circuit has an internal short - just unplug the unit and see if your problem persists. If there is more than one circuit, pull all the fuses for the circuits and then plug them in one at a time to determine which one you're dealing with, then the wiring diagram will show you what's attached to that circuit. Essentially, you need to find the power wire that feeds the problem circuit and then see where it's shorting.
Because the problem has caused some things to run "degraded", I'd suspect that you have a partially "fried" wire somewhere that's causing a high resistance. Look for burned insulation or some indication that electrical arcing has occurred. I'd suspect any non-factory wiring. When you have everything open, you can try to get it to short/arc again - you may be able to see or hear where it's at.
With all the wires and components, there are a lot of combinations of things that could cause problems, have a look under the console and let us know what you find, then it should be easier to narrow down the problem area.