I just created a MovableType blog and I notice that my calendar is being clipped when viewing with IE6 based on what I have my text size set to in IE.

At the smallest text setting, I get the entire calendar. At the medium text size I only get a few pixels of Saturday.

At the Largest text setting I only get Sunday through Wednesday visible.

It appears that the size for the links div is fixed width but the calendar gets resized based on text size.

Here is a link to my blog to see it: My Blog

Since the calendar class uses relative font sizes instead of absolute, that's not unexpected. You could set it to an absolute value in your stylesheet instead.