Single/Multi selection parameters empty

I'm using CR 2011 v14.0.0.760 RTM and it has been working fine under Win7 Pro SP1 for quite some time. I last used it Friday and all was well. This morning I tried to edit a report that has single and multi-selection parameters and the criteria screens display no data for drop-down and list boxes. As a test, I created a new report with one parameter and entered the data as follows:

When I run the report, I'm presented with this screen. Every one of my reports has this problem now. I did a repair of the Crystal install and rebooted but to no avail. I've since requested a full reinstall but I was wondering what could have gone wrong here. To the best of my knowledge nothing changed. Could a Windows 7 update have done this?

Thanks

Carl