TWAIN Driver - I'm Lost - HELP!

Hi,

I hoping someone can help me with a small technical conflict I’m having have with my scanner. I have an inexpensive scanner (Canon Canoscan FB320P) which communicates with my laptop via the parallel port. I also use the same parallel port for my printer. I swap the cables depending on which device I need. Here’s the problem I have when trying to import a scan into Photoshop via the scanner:

TWAIN_32 Error Message

Could not open the TWAIN source. Make sure there is a valid source for your scanner in the TWAIN directory found in the Windows Directory.

Scancraft Error Message

The parallel port may be used by another application. Error code: 0x00060800

Can anyone offer some expertise as to how I can configure things so that the parallel port recognizes both devices depending on which is plugged in?

Very much appreciated. Thanks in advance to anyone who could help.