Vista has enough of its own problems without having to concern users with third party software issues, yet, they do exist. Symantec made a partial admission that its SymProtect feature was responsible for registry corruption during both Windows XP SP3 and Vista SP1 upgrades. The company recently delivered a software utility to locate and repair these registry problems.
If the SymProtect process was running during the installation of the Service Pack this would prevent a Microsoft utility called Fixccs.exe from executing which deletes registry entries created during the installation process. This is what would lead to the corruption problems.
SymProtect is designed to protect Symantec’s security suite from being attacked by any kind of malware and this is why it prevented from Fixccs.exe from running.