Harv, It's Not Normal...

...although it is strange that you've had the problem with 3 drives. Most of the replacement drives that we get are not Maxtor...(Usually Western Digital because they're cheap. LOL) We've had a few Maxtors, but I've never had that kind a problem. When booting up or running a defrag, some drives will make a slight amount of noise, but I sure wouldn't call it a "clicking" noise...

Either way, since your diagnostics tests are showing problems and you continue to get bad replacements, I suggest getting your money back and trying another brand.

Hope this helps.

Grif