It simply means that you still have some blur effects in your timeline. Remove them by hand and replace with the new version. There is no automatic way to do that.
Does that mean that all Gaussian Blur effects from past Premieres are now outdated and must be individually replaced? (I have dozens in some sequences). It is funny because for some clips the effect still seem to be sitting in the effect controls and others it has disappeared completely.
That is one of the reasons why it is generally suggested to finish your projects in the version you started with, and not upgrading current projects to a new version. Now you may have to find each instance of the blur effect manually and replace it with a new blur effect. It's your choice.
One of the differences with CS5 is that it is for 64-bit only. That means that 32-bit Effects will very, very likely not work in it. Replacing them with the 64-bit version is about the only way that I can think of.
As Harm points out, finishing a Project in the version in which it was created is the best course of action.
OK thanks. Unfortunately, I am always re working parts of old projects into new ones, but redoing the filters is not the end of the world. I’ll reinstall CS3 for older projects that don’t need much new editing ... there is also a small problem with scratch disks in CS 5 -which automatically defaults the scratch disk information into the “same folder” when opening old projects into CS5 - unless they are nested.
I just re-checked the project. I removed the obsolete and replaced the Gaussian Blur with the new one. However of the 6 clips that had Gaussian Blur only one needed replacement (form 6 years ago); the filter worked fine on the other 5 (newer CS3) clips. The warning still pops up when opening this file. I just ignore it since it is incorrect.