controller goes haywire when run off battery instead of USB

Hey guys,

I'm having a real frustrating problem here...

I wrote some pretty simple firmware based off the heavy project, which I compiled and uploaded to the controller over USB without any real trouble, problem is, that as soon as I try to power the sucker with a 9v battery instead of the USB it goes haywire!  However, when I plug in the board with USB everything works precisely as expected.

I have 3 sharp GP2D12 IR sensors hooked up, as well as 2 continuous rotation servos.  I run the servos off a seperate 6v battery through the servo power in, and power the board with a 9v battery through the main power terminals.  I've tried all sorts of things to try and get some idea what's up but ultimately it just goes nuts when it's on battery.  Any ideas?  If I start up the board with the 9v, the board acts crazy, but then if I plug in the USB, it suddenly stops being wierd and works right.  It's the darndest thing.

I can post my code if it would help.....

I will try with fewer devices connected when I get home, but I doubt it's a lack of adequate power.  I tried it with a 12v 8xAA battery pack powering the controller and got the same behavior.  I have the rangers set to draw the 3.3v from the analog input vin terminal.  How would I check the 5v line on the board?  Would adding a 9v 1.5A regulator between the battery pack and main power terminal help? 

welp you were right liam, it was the 9v.  On the 9v the 5v regulator only was reading 4.5v at it's terminals, so I swapped fresh cells into my 12v pack and tried that again, and it works fine now.  BOy this thing needs a lot of power :-/  Hopefully the 12v pack through a regulator will be enough!  But I'll know to keep an eye on the 5v and 3.3v regulator outputs now, Thanks!!