USB Mouse stops working

I use Ubuntu Hardy Heron 8.04 and a Logitech USB Optical wheel mouse and my laptop has 4 USB ports (it's an Acer aspire 5720). The mouse initially worked fine but then after several weeks of use, when I plugged it in to its usual USB port, the light would come on for a few seconds then go out and the mouse cursor would not move. Plugging it into a second USB port normally fixed the problem until that port began to reject the mouse. I then moved onto the third USB port and THAT began to reject it. Finally the fourth port worked but now that has now rejected it.

It is usually possible to get the mouse to work eventually by plugging the mouse in several times but it's becoming a pain now. I'm pretty sure it's not the mouse itself .

Could anyone give me an idea how to proceed ?

Kerry