HELP PLEASE

First of all I would like to thankyou all for helping me out with an earlier problem

much appreciated ;)

Now my father inlaw has a strange thing going on with his scanner ,he has a canon canoscan lide 20,he can get the scanner up on screen but, when he goes to san a box comes up saying "unable to find twain source"this has only happened recently,so it is a bit of a puzzle.

He has uninstalled and reinstalled but to no avail :he has looked everywhere for twain but it has gone please can anyone advise :(

he is on windows xp aol, with avg,ewido s&d CCleaner and spyware.

thanks in advance