M-Audio Keyboard 49e disfunctions after some time

I have an m-audio 49e keystation that works perfectly fine with my laptop .. until it suddenly becomes undetectable. I could be doing anything - playing on the keyboard, recording midi, or not even touching it; and after a while it will just 'disappear' and no sound will play from it anymore. The lights on the keyboard is still on, but it just remains undetected. Then even if i take it out from the USB port and put it back in, or restart my sequencing software(s), it remains undetected. I have to restart the WHOLE computer for it to be accessible again. The time it takes for the keyboard to stop functioning varies very widely - sometimes it could stop detection after just 5 seconds of opening my sequencing software, sometimes 10 minutes, sometimes even after an hour.

Please help me. It is really hard for me to do work fast when i keep having to restart the computer.