CalendarExtender loses style when placed inside a web user control.

Fix1: http://forums.asp.net/p/1068114/1550697.aspx
As a workaround, try this - in the page that loads the usercontrol:
1) add another textbox to the page, outside the updatepanel
2) add a calendar extender and point at the textbox
3) on the textbox set 'style="display:none;" so it doesnt' show up on the page.
This should get the styles loaded early enough so this doesn't happen while we figure out a fix.
Fix2: Don't know how much this helps but I noticed that if you set EnablePartialRendering ="false" the script manager the original css is retained.