Use newer or other browser versions. With IE8, reloading the page helps to mitigate the issue. For IE7, restart the browser as frequently as required to avoid outages. Increasing the client system RAM memory mitigates the issue partially.
Adobe supports CQ/AEM running on the documented platforms. If a bug in a specific platform, or third-party component, impacts the use of CQ, Adobe makes reasonable efforts to provide a workaround. However, Adobe can't support the platform itself (it can't fix any bugs in third-party components).
A Microsoft bug causes this IE7/IE8 memory leak issue, and there is only one possible workaround, as noted above.
As recommended steps to mitigate this issue, ensure that you limit the number of open windows/tabs while working. Also, restart the browser from time to time, if you are involved in intensive authoring in CQ.
An alternative solution is to use a browser from another vendor, or upgrade to the latest version of IE (which has greatly improved Garbage Collection functionality).