Keyboard malfunction on dell notebook

my keyboard on Dell inspiron 1501 from 2006, malfunctions. after either browsing the internet or waking out of sleep or locked mode i find that as i type the pc displays a sequence of characters in order (e.g.-- qwerty...or hjkl;'zxcv,.. --just as the keys are set up on the keyboard. No matter what i am typing (random letters or regular words, it displays these sequences. rebooting corrects the problem, until it appears again after a browsing session or wakeing out of sleep.. virus/spyware scans show no infections. anyone know how to fixit?-- oops! apologies for repeated posts.. ;(
Thankyou
CP