I can't turn my olympus digital voice recorder WS-450S on, even with a new battery, i hadn't used it in a while, so i was shocked that it didn't work. It only turns on if i plug it in to the computer, but otherwise the screen stays blank and it won't turn on.

I've got this same problem :( Turns on when I plug it in to the USB, stays on when I disconnect it but if I turn it off I can't turn it back on again. It is showing a "battery low" warning and I tried to charge it via the USB last night, but it seems to stop charging after a while and despite being left for a good time last night, this morning it is the same and I've had another battery low warning.

I've just found the full pdf manual online, and have found (on page 80) a reference to it not always behaving stably when connected via a USB hub. I'm going to try to charge it via a direct port and see if that fixes it.