this specifically:
PopCap seems to have a god awful Steam Cloud save implementation, shame on them. After mucking around with this for a while, seemed like somehow my save file stored in the cloud was corrupt and just couldn't be recovered. (That is, my user1.dat file was stuffed. I tried the trick to rebuild my users.dat file, but it didn't work.)
Anyhow, I managed to clear my save data this way, so I could at least play PvZ again:
- In the game properties for PvZ, turn off Steam Cloud sync.
- Find your cloud save folder for PvZ in explorer. E.g.
C:\Program Files (x86)\Steam\userdata\(your user number)\3590\remote
- Delete all the files in this folder.
- Start PvZ again. It'll ask your name to create a new profile with and won't crash. Hurray! But we're not done yet.
- Turn Steam Cloud sync back on and start PvZ again. Steam will present a cloud conflict dialogue; pick local files/upload to cloud.
- PvZ will create a new profile for you again.
- You can exit PvZ and the new profile will then sync back into the cloud and it should be all fixed.
Hope this helps.