My Canoscan lide 35 worked fine on my XP machine.  Now attached to my vista
machine and it worked for awhile and now it is not working.  I went to Canon
and downloaded a file to update the drivers.  It was a .exe file that ran, I
saw a few seconds of files unzipping and the like and then it was done.  
Still, does not work.  I have unplugged and replugged the usb connection, the
system says it installs the drivers, still no joy. I get two error messages;
the first says "inable to communicate with scanner".  When I close that
message box I get "Unable to open TWAIN source, please check connection...".
When I check the control panel, hardware. scanners and cameras, it is listed
but in Properties it reads "unavailable".  Oddly, the top of the properties
box lists it as "canoscan LIDE 35 #2 Properties" (note the #2...?).  When I
look under Device Manager, Imaging Devices it lists the Canoscan Lide35, and
the properties list it without the #2, and says "this device is working
properly". I tried to uninstall it, but the program still shows in the
"Uninstall Hardware" tool but cannot be uninstalled?!  With the "...#2"
thing, I wonder if there is a conflict?  Oh, I rebooted numerous times as I
tried the various functions...

So I tried everything I could think of and it still will not work.  This is
a Dell inspiron 530 blah blah blah...

What's next?  After I get this working we can tackle the conflict with the
Canon printer...