I'm sorry I don't have a solution; I'm jumping on your question because I have a similar issue.
First the archives for 2009 and 2010 totally disappeared.
So I went into the widgets and indicated, deliberately, to include years 2009, 2010, 2010. This restored the archives, however 2009 and 2010 are listed beneath January 2011. So it's funky.
An after fussing with this, a weird space thing changed in my entire widget column. All my widgets are spaced much closer together than they used to be. And the widget (meta) directly below the collapsing archives is indented differently and spaces itself too close to the previous widget. The whole widget bar has gotten reformatted or something.
It seems to be an issue that starts from the collapsing archive --
Although I tried simply removing the meta widget (beneath the archives) and when I did that, it removed with it every text and widget that was positioned beneath it. So is it related?
I appreciate, as always, any suggestions.
Visit my blog and look at the bottom of the side bar (on the right) to see what I mean.