When using the content editor web part, in some cases you can receive the following message when editing the content, or saving the content: "cannot retrieve properties at this time".
This exact error suddenly appeared on a client installation after https access was enabled via ISA server. Prior to that the content editor web parts worked normally over http. When browsing the site using the server name there is no problem. The issue therefore lies with the https translation.
The sites alternate access mappings are configured with the https url as an extranet. Changing this to any of the other options makes no difference.
Mart Muller refers to a MS KB article in his post here however I'm not sure this is correct. Neither of the two supposed causes are applicable in this case:
You configure an Internet Information Services (IIS) virtual server that has an assigned IP address, and then extend that virtual server by using Windows SharePoint Services.
You configure an IIS virtual server that has a host header name, you extend that virtual server by using Windows SharePoint Services, and then you install Web Part assemblies in the Bin folder instead of in the global assembly cache.
Further investigation ongoing...