I recently bought the Belkin 6-Port Firewire adapter. Right now I have two external HD's ( 200 GB and 300 GB ),and my iSight connected. I was wondering if it was safe to have my two HD's always connected? I've been having issues with my screen turning dim and not coming back to normal until I restart. I reset the PRAM and still after using my iMac for awhile the screen turns dim, like as if were about to go to sleep, but when I try to brighten it, it stays the same brightness?