According to Microsoft the anticipated
Service Pack 2 (SP2) causes problems with more than 40 programs. http://support.microsoft.com/ has information from Microsoft on this issue.

Apparently some programs stop working
after installing SP2. Some of these programs are Symantec's Antivirus Corporate Edition 8.0, MacAfee's NetShield 4.5 and CA's eTrust 7.0, and even a few Microsoft programs.

IBM has informed employees not to install the Service Pack out of fear that it might cause problems with current applications.

Source