Black screen from scanner

I have just re-installed my scanner (CanoScan D2400) because I had to switch computers. When I click to import from it, I sometimes get the message that the Twain driver cannot be found and to check my Windows directory. When I try again, my scanner opens but it only shows a black preview screen? This was working perfectly and my diagnostics test says it is working okay. Anybody any idea what my problem might be?

Eugene

The actual message I get is,
"Could not open the TWAIN source. Make sure there is a valid source for your scanner in TWAIN directory".
When I search MY COMPUTER, my scanner is listed in the TWAIN directory! I just installed Elements 2 to see if that worked and I get the same message which suggests to me that it is a scanner problem yet the scanner seems to be working (apart from this black screen). I just can't figure it out, Eugene