I have a pixma mp500. I have a pixma mp500 printer scanner. The printer works very well but the

Question

I have a pixma mp500 printer scanner. The printer works very well but the scanner is another story. I set up the printer per the manual, loaded the software and tried it out and everything worked. I turned both the computer and printer off at the end of the day and when I started them the next day the printer works fine but the scanner won't scan. When I try to scan a document I get a scan failed message on the screen.I reloaded all the software and started all over again and it sometimes works and sometimes doesn't.It's getting extremely frustrating.Please help,George Saling