Is there anything in the Application Event Log?
The only error I've ever gotten installing the service pack is running out of disk space. <sheepish grin>
Event Type: Error
Event Source: MsiInstaller
Event Category: None
Event ID: 11601
Date: xxxxx
Time: xxxxxx
User: N/A
Computer: xxxxxxxxxxx
Description:
Product: Microsoft .NET Framework 1.1 -- Disk full: Out of disk space -- Volume: 'C:'; required space: 46,724 KB; available space: 38,048 KB. Free some disk space and retry.