Yesterday Garmin released GE 5.6.0.
https://forums.garmin.com/forum/garm...-release-notes
What the release notes don't say is that it'll now only run in Win7 (v5.5.0 runs just fine in Vista SP2) or above.
If you're using v5.5.0 in Vista SP2 it'll update to 5.6.0 just fine--it just won't run.
FYI the GE download page at
http://software.garmin.com/en-US/express.html
says that Win7 or above is required although I still got 5.5.0 via the download link.