I have noticed a number of issues with service pack 2:
1) On a laptop, SP2 locked up on its first reboot. Fortunately after booting into safe mode then rebooting, the problem seemed to clear up.
2) On a desktop, SP2 apparently conflicted with the NVIDIA AGP card. The system would not boot at all with the AGP card as the default (even in safe mode). I set the PCI card to be the default video card and booted in safe mode. I was successful at returnning to a previous restore point.
3) Was unable to access secure Internet sites when using a proxy server...This solution isn't in the KB article mentioned here, which is the main reason I am posting. The problem was that IE has changed the way it handles proxies slightly in the IE / Tools / Internet Options / Connections settings page. Now you must explicitly put the proxy server address on each of the individual lines under Advanced (HTTP and Secure). Previously IE used the setting from the Connection tab for both unless it was otherwise specified in the Advanced Proxy Settings pop-up.