Did OK for photos, not ok for negatives or slides

Received this scanner for Xmas. Worked very well for the first two weeks on photos and negatives but so-so on slides but the slides are 40 years old and have darken and lose of color over time. In the last two weeks started getting very grainy scans from time to time and lots of cooties (artifacts) on the scans, then started getting two colored stripes, one red and the other yellow down the center of every negative scanned. The colored stripes moved closer to the center and now they have merged into one color, purple, right down the center, on all negatives. Even rescanned the negatives that came out fine and now they too have the purple stripe on them also. Contacted Canon and said to Calibrate the scanner 4 times in a row, but that didn't help. Then it was suggested to download the latest driver and software to correct the problem, but that didn't help either. They said it probably has a problem and needs to be sent in for repairs. Sent it back to place of purchase and will now try the Canon CS8800F Scanner instead. When it (4400F) worked, it did a good job. Also the photo editing software that comes with the scanner is somewhat lacking. Using Adobe PhotoShop Elements 6 instead.