I have two memory sticks (loads of space on both of them.) For about seven days now I noticed that they are incredibly slow (about usb1 speed) and I don't know why? I have 10.5.4 OS , 2 x 2.8 Ghz Quad, 8 GB Ram with about 5 usb2 ports. I tired ports at both the back and front - same result. Any ideas ?