PSPad is 32 bit's application and 32 bit's process is limited to 2GB of memory (even you have terabytes of memory, it's operating system limitation). 1.2 GB file itself consums 2,4GB of memory (cause unicode) and you are out of limit.
In the future, PSPad will be available in 64b version too, but now you need to choose another tool. -- <http://forum.pspad.com/read.php?4,66620,66621> PSPad freeware editor http://www.pspad.com
