Problem with Rundll32 in Win 98 SE

I tried posting this in another section of Win 98 but no help.
Please help me if you have any suggestions

My wife has a P2, running Win 98 SE, with 458MB of RAM. She uses a
Lexmark 6250 series All in One Printer/Copier/Scanner for emailing
photos of the grandkids. Everything has been working fine until
recently, when the scanner portion of the All In One stopped working.
The copier and printer portion work fine,

The help desk of the Lexmark ssupport folks helped me isolate to the
printer of Win 98 operating system. During the fault isolation process
I got an error message having to do with Rundll 32. The message says
something like
("Rundll 32 has created an error)The Lexmark folks felt this could be
the cause of the problem.

I hooked up the printer to my system ( a P4, Win xp, 512 MB of RAM)
loaded the printer software and all 3 functions of the All In One work
as advertised.

QUESTIONS

1. What exactly does Rundll 32 do?

2. Any suggestion on fixing the problem?

TIA Loring H.