Hi
We recently switched production from CS4 to CS5, and we encountered a really bad problem.
When opening a file and fonts are not loaded, the splash screen that appears does not show all missing fonts or in some cases no fonts. As you would understand this is a really huge risk when reopening files and not knowing what fonts are not loaded.
It has nothing to do with font cashes, we have this on all computers (90+ installations) here and in CS4 it is OK.