I did have a look at the Chrome plugins:
Weatherflash doesn't seem to work with the Shockwave Flash 10.3 r183
it works OK with version Shockwave Flash 10.1 r102
I disabled the first one. Now it weatherflash works OK.
Don't know if this is secure because version 10,3,183,5 was a security update. But it works now.
Chrome automatically updates the plug ins so I guess a lot of users will encounter this problem
To disable automatic updates add --allow-outdated-plugins at the end of the target rule in Chrome
It should then look like: "C:\Program Files\Google\Chrome\Application\chrome.exe" --allow-outdated-plugins