I am having the same problem as Peggy. It was fine until today. When I try to insert an image, all seems okay until I click "insert into post" and then the screen goes white.
I went through timethief's list:
Are you using http:// or https?
I have changed it to https.
Exactly which browser and version of it are you using?
Mozilla/5.0 (Macintosh; Intel Mac OS X 10.5; rv:10.0.2) Gecko/20100101 Firefox/10.0.2
Have you tried clearing your browser cache and cookies?
Is your browser version up to date?
Have you tried using the browser with all extensions or add-ons disabled?
Do you have third party cookies enabled?
Do you have another browser you can try?
Tried safari, same thing. (Although my version is not up to date. The new version seems to be for snow leopard and I am using leopard.)
You can use this link to see if your Flash is up to date.
Done – installed 10.3
Any thoughts would be much appreciated.