In shared web hosting, the ability to use your account is limited not just by your space and bandwidth, but also by how much of your server's resources (processor and RAM) you may be able to use at a given time. Since you are sharing a server with many other clients, each must operate their site within certain limits to ensure that all accounts perform as well as expected.
We also completely understand, however, that owners are often unaware of instances where their site is using too many resources, and that such usage is not done maliciously. Our staff is dedicated to handling resource usage issues and working with clients to resolve them. With that said, there is a chance your site will be suspended if issues can not be resolved in a timely manner. Most likely, however, we just ask you to upgrade to a server that may better handle your needs.