The sidebar on my site is not working in IE.
I just upgraded the version of WP this morning to 2.21 to see if that would help.
All plugins are currently deactivated.
It also does not show in the new Safari (version for Windows).
It did work a few months ago. I don't know exactly when it stopped working in IE, since I generally only use FF.
I'm thinking that the top picture graphic on the PC Doc site might be different in size than the other site, so I'll play with that and see what happens.
Now, be nice, since this a Sunday, but I do not have the time to check the page for validation. I chose WP because I just wanted to publish, not code, even though code is a beautiful thing.
I'm not trying to be flippant, but if that's your only advice, please move on. This support question is not for you.
Any and all other responses will be gratefully appreciated.