I’ve read a lot of horror stories where Amazon has randomly closed people’s accounts for different reasons. Fair enough – many of these are due to breaches of their terms and conditions (e.g. failing to properly disclose links, not using the appropriate images and links provided in the affiliate dashboard, buying from one’s own affiliate links, etc.) but yes, if you fail to comply by their rules, you’re at risk of being shut down (and losing all the commission you’ve racked up). SO, don’t be a dummy, read the terms and conditions thoroughly and make sure you’re not breaching them.
You should also make sure you aren't competing with your own affiliates for eyeballs. Any marketing channels you're using, such as search engines, content sites or e-mail lists, should be off limits to your affiliates. Put marketing restrictions into your affiliate agreement and notify partners immediately. It's your program--you set the rules. Or, if you prefer, you can let your affiliates run the majority of your internet marketing.