USB port problems on my Macbook Pro

I have a Macbook pro , bought in Aug 2008 , Aluminium body , running Mac OS X version 10.5.8
I am having problems with my USB ports on both sides. Primarily the R/H/S .
When plugging a device in , within seconds a warning comes up saying :

Device Removal .
" The device you removed was not properly put away ....etc "

This happens very frequently using the right hand port and almost every time with the left hand one.

Any ideas .

Cheers , Jay