$obsdisclaimer This issue has been resolved with the latest update to ACT! 2010. Please see the following Knowledgebase Answer for instructions to download and apply this update:
Answer ID: How to Download and Apply the ACT! by Sage 2010 (12.0) Hot Fix 4
This issue has also been reported to occur regardless of applying the ACT! 2010 Hot Fix if you have removed the Layout Selector icon from the ACT! toolbar.
You can resolve this issue by resetting your menu and toolbars back to default settings by by performing the Reset Menu and Toolbars command, by clicking on the Tools menu option and selecting the command from under the Customize submenu.