iMac won't boot with external drives attached

[oli.watts]

Hi,

Facing an odd problem...

I've got two external HD attached via USB to my iMac (the most recent, Aluminum version) which is running 10.6.6.

If I restart the machine with the drives attached the system hangs at the first all-white screen, and doesn't even display the Apple logo.

Remove the drives means the system boots fine.

Any thoughts on fixes?

Cheers,

Oli

 

[simsaladimbamba]

Try an SMC reset:
Intel-based Macs: Resetting the System Management Controller (SMC)

 

[DewGuy1999]

Make sure your iMac's internal hard drive is selected at the Startup Disk in System Preferences.