Looking for help with a laptop usb issue

Hi All,

ill just get straight to the point i have an acer aspire 5740G laptop with 4 usb ports on it and the other week i plugged a;

"4 port usb hub with independent power supply"
into one of the ports of the laptop so i could connect a few more devices

and immediately when i plugged the hub in with the other devices already connected to the hub and the independent power supply connected and switched on

a notification icon came up with something to do with a power issue and immediately two usb ports that were never connected with the external hub dont function properly but the two on the other side of the computer still worked flawlessly one of them being connected to the hub

now when i say dont function properly; when i connect my mouse or keyboard to the two ports that are failing a message comes up saying the device has malfunctioned, and dosent install drivers properly i have tried uninstalling drivers and scanning for hardware changes and it hasnt solved the problem even taking the battery out for a while and rebooting, and having a look in the bios which dosent tell me anything about the usb ports

but the two ports that are playing up will detect my external hard drive and the device shows up in my computer

one thing i have noticed is that the computer still thinks that the external hub is connected and it says i have 8 ports when i only have 4 two working and the two that dont work properly... any suggestions much appreciated =)