First, if you connected the data cable to the computer, uninstall the current driver and then unplug the data cable. (This is for USB cables.) To uninstall, open the Devices and Printers control panel (click start and then find the line on the right hand column). Right click on the unit and click on Remove Device.
Then navigate to http://www.usa.canon.com/cusa/support/consumer/printers_multifunction/pixma_mp_series/pixma_mp210#DriversAndSoftware
and select your version of Vista (32- or 64-bit). Download the software/drivers. The MP Navigator is the full software and will let you launch scans from the unit once you set it up. The first driver in the list is just the basic driver and will only work with scans initiated by the computer.
Always launch scans from the computer first. There are buttons in the MP Navigator that match those on the all-in-one. The default settings for these need to be set up (see the help in the program) and include resolution and location to save files. Then when the monitor program is running, you will get the MP Navigator coming up with a button press.
Vista can scan without the MP Navigator with three included programs: Paint (File > Import from Camera or Scanner > New Scan), Windows Fax and Scan (New Scan) and Photo Gallery. Howevver, if you do not install the Canon driver, you will probably get a printer driver only from the OS.
If the problems persist, try a new USB cable and a different port. If you use a USB hub or print server, try a direct connection. Scanners require bi-directional communication with the computer and can fail when the printer works.
I hope this helps.
(if the copy function works, then the above information should help. If the scanner itself is not moving, check for a transport lock and that it is lighting up as it should. In the last case, the unit may need service.)