Don't know if this will help...But, the scans are typically saved to the Work folder in program files under RW-240, you'll have to drill down to them. If the customer is scanning to a set, scantool always tries to open the last set you worked with when you open the application. If one of the tif files have been moved it will display a similar error to what it seems you're experiencing. Try creating a set and saving it, then closing scantool and reopening it. If this works that is probably your problem. It seems the biggest problem with this software solution is...you guessed it human error.
I've seen the error, the extra \ and if they are using Tifs which my customer was the extension.