I just purchased the full version of Delphi XE Architect after using the trial version for 30 days. I can't build anything, every time I go to build a project I get the error.
[DCC Fatal Error] MegaMainPrj.dpr(1): F1027 Unit not found: 'System.pas' or binary equivalents (.dcu)
A quick google said that the library paths were a problem and I compared what was given (in a previous stackoverflow question) with what I had in the registry, and it was identical.
What could be causing this?
EDIT: Immediatly after I get this error message the entire IDE crashes.
Make sure you have the environmental variables set properly (Tools->Options->Environmental Variables from the IDE's main menu):
BDS=D:\Embarcadero\RAD Studio\8.0
BDSCOMMONDIR=C:\Users\Public\Documents\RAD Studio\8.0
PLATFORM=Win32
These should all be set in the System Variables section, and should have been added by the installer. (Obviously, they should point to the installation location of your XE installation - mine is installed in D:\Embarcadero\RAD Studio\8.0, as you can see.)
EDIT: I see in your comment you installed in C:\Program Files - bad idea if you're running Windows Vista or Win7 or higher. You should try installing in a different location. You can also try running the IDE as Administrator (right-click shortcut in Start->All Programs->Embarcadero->RAD Studio XE->Delphi XE, choose "Run as Administrator" from context menu). Does this change anything?
Also, you can open a free support case at Embarcadero for installation-related issues. I'd first try reinstalling in another location (running the install as Administrator, putting it in another folder, and installing for all users); if that doesn't work, open a support case. You can also post to the Embarcadero Delphi Installation forums - you'll need to have already created a user account there first to log in.