Outlook 98 IPF in module MSO97.DLL at 01

Some of our users get this error message when trying to user Signature Picker in Outlook 98. Our developers and support people are unable to resolve this. We contacted our Compaq support package people, no luck. We’ve tried all available info from our Technet subscription. No luck. About 15 of our 700+ users have had this problem. It has to be a registry setting. If we reclone their PC it goes away but of course they lose their individual settings and we have to spend 2-3 hours getting them back to where they were. To solve the minor annoyance of not be able to select a custom signature just doesn’t really warrent the time needed to correct it. We have tried replacing the MSO97.dll but the problem remains.