Do you use Windows XP, Vista , 7 or 8 ?
There are many reasons, which can cause this problem. I will give you a link below, please try to follow each and every steps on that page and let me know the result. Try this on one computer and if you are able to solve the problem then, try it on the other.
OK, thanks for the update, so you have already installed the scanner driver. Can you tell me, what exact error message,you see on the printer screen, when you try to scan ?
OK, are you replying me from the XP or 7 pc ?
OK, we will try some test of the Windows 7 PC and then we will try to do that same test of Vista. Follow the steps on your Windows 7 PC and let me know.
Before you begin, make sure your scanner is properly installed and turned on.
Click the Start button ,click All Programs, and then click Windows Fax and Scan.
Click Scan in the bottom of the left pane.
On the toolbar, click New Scan.
In the New Scan dialog box, click the Profile list, and then click Photo. The default settings for scanning a photo, which you can use or change, are automatically displayed.
To see how the photo will appear when scanned, click Preview. If needed, change your scan settings, and then preview the image again.
Do you mean you cannot scan from the Vista computer or you cannot open Fax and scan program in Vista ?