Here are some of the details:
MS security update KB918118 causes the rich edit text control used for creating and editing text objects in Inventor to discard all input resulting in an empty text string. A hotfix for this issue should be available for download on March 2, 2007. The hotfix will be available for the following versions of Inventor:
R11 DWF Extension SP2
The hotfix should be available at the following locations - just select the version of Inventor you presently have installed.