build 3453 is a pre release beta build of DWCS3 that has a known bug with floater panels such as a re used for the eCart object.
the realse build of Dreamweaver CS3 was build 3481. eCart will not work in build 3453 of DWCS3
it should not be an issue in DWCS5 though, fro DWCS5, Delete the Dreamweaver Cache file from the users configuration folder:
common_installation_issues.pdf