zotee98 could you tell us what switches (model numbers) you have and what they control? Have you switched to any energy saving CFL's?
The first thing you might want to look for also, is something new added to your home. A video game unit, new TV anything electronic or something with a power supply. If you have added something try unplugging it (just turning it off may not work) to see if your setup starts working again. It sounds like a noise or signal sucking problem.
(http://www.bdshost.com/X10/lpup.gif)---(http://www.bdshost.com/X10/lpup.gif)---(http://www.bdshost.com/X10/lpup.gif)---(http://www.bdshost.com/X10/lpup.gif)---(http://www.bdshost.com/X10/lpup.gif)----KDR