"Could create temp file" error

Hi all,

Does anyone have any idea what the following error could mean?

"EXCEPTION WHILST EDITING PROJECT FILE: Could create temp file."

This happens using the InstallShield standalone builder. The project it's trying to edit has two releases (32-bit and 64-bit) and the first release builds ok, not the second one.
I guess the error should say "Could NOT create temp file", but I have no idea what temp file it is on about.

This is a strange one, and google-ing it has not really returned any useful information. So any idea that could point me to the right direction is more than welcome.

Thanks!