Most TWAIN issues with LIDE/CANOSCAN scanners can be solved by performing a clean installation.
- Unplug the USB cable from the scanner and run the DELDRV.exe (uninstall utility) program from the CD, or download it from the Canon website.
- Cut the power or turn off your DSL/CABLE internet modem.
- Unhide your system folders by RIGHT click on the START button, then LEFT click EXPLORE. Click on TOOLS on top of window and select FOLDER OPTIONS. Click on the VIEW tap, then click on SHOW HIDDEN FILES AND FOLDERS. Hit OK and close out of everything.
- Click on START and select RUN. In the RUN window, type MSCONFIG. System Configuration Utility will pop up. Click on SELECTIVE STARTUP, then take the check out of LOAD STARTUP ITEMS. Click APPLY and then CLOSE and restart computer.
- Run the install from the CD as normal and Restart again. Once computer is back up, THEN PLUG USB CABLE BACK IN. Perform a scan.
- Go back to MSCONFIG and click on NORMAL STARTUP, APPLY, CLOSE, and restart once more. You will then be able to reconnect to your internet modem.
WIN XP does not like having two USB scanners/software loaded at the same time. Microsoft has an article about it. You MUST remove/uninstall previously loaded scanner software. Also check the TWAIN_32 sub-directory in the WINDOWS/WINNT directory and make sure that only the CNQxxx folder and WIATWAIN.DS file are the only things in there. If you already have another imaging device installed (webcam, digital camera) you may have to uninstall those before the scanner software has been loaded in, then reinstall the other devices.
This solved my problem with CanoScan Lide25 which continuously gave this error before “Unable to open TWAIN source please check connection then re-start toolbox”