Arduino and RS232 getting very hot with external power supply

I currently have the Redpark iOS Breakout Pack connected to my Arduino, when I run it through the USB it doesn't get hot however when I use a 7.5V 1.2A rated DC power supply both my Arduino and the RS232 TTL to Serial get incredibly hot (within under a minute), is this cause for concern or just normal?

Incredibly Hot ? Never Good.

Concern. Sounds like power is reversed from the Adapter.