I tried re-installing Chrome, but that did nothing. A web search suggested changing the settings in the Customize Start Menu dialogue, but this had no effect. Then I found a site that mentioned a shell extensions as a cause - not an extension I had installed, but it got me thinking.
The only thing I had installed recently was a Netgear ReadyNAS Ultra 4 that I'm reviewing. This comes with a backup tool from Memeo, which installs a shell extension; it adds a context menu (right-click) entry for easily selecting items for backup.
I tried uninstalling this (luckily it installed as a separate program item) and the problem was immediately fixed. So if you're having similar problems with jump lists, check what third-party tools have been added to the Explorer context menu and try removing them.
|Shell extensions can sometimes play havoc with Windows 7's jump lists|