Acer TravetMate280 usb detect trouble

I have a problem with my Acer Travelmate 280 USB(2) port.

It is not able to detect an external 2,5" hard disk.

I have Win XP installed with no service pack on it.

I also had a similar problem trying to detect my digital camera or a memory stick but if I turned off the computer and start again finally the USB ports detected them.

I have tried this way too with the hard disk but it does not work, no detection at all.

Please, can anyone help me?! Is it a drivers problem? or is it a BIOS configuration mistake? I don't know what to do.

Shall I install the Win XP service pack 2? Shall I update the BIOS?

If it is any of those things, please, tell me where can I download the latest drivers or bios version. I've tried the acer download page and it doesn't seem to work.

Thanks a lot!!!

Golfrund