I was trying to install VS 2005 SP1 on Windows Server 2003 last night but kept getting an error about an invalid signature (or something like that anyway – can’t remember the exact error now)
The cause of the problem as stated on the Microsoft websiteis *“This problem occurs when the computer has insufficient contiguous memory for Windows Server 2003 or Windows XP to verify that the .msi package or the .msp package is correctly signed.” *
The solution can be found here.