This may cause if the following registry entry error…..
Now try the below:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion and on right side the value is “ProgramFilesDir”, just type “REG_SZ” (without quotes)
Double click this value and set the data as c:\program files (if it is loaded in C drive)
Remember, before doing, must take the necessary backup of ur data and registry !
OR there is a better way to download SP2 and install it manually.
For SP2 Deployment and Installation.
And for SP2-Updates.