System requirements for version 4.0, nor system requirements for version 2009, ever mentioned Windows 7.
Your version 4.0 is an old product, released in 2006 (Waaaay before Win 7 existed). Expecting a developer of any software to go that far back, and to work on a fix, is unreasonable.
Either update to version 2009, or wait for the upcoming version 4.2.
Even the version 2009 doesn't list Windows 7 in it's system requirements. However, people use it, and it works just fine. And just in case 2009 installation does encounter Win7 incompatibility, you may request, via email, a patch.
But remember even v.2009 was released before Win7. (Version 2009 is a product that released in the summer of 2008.)
Better wait till the upcoming v.4.2 comes out. It will be 100% Windows 7 compatible.