IMac Hanging

[JSMac2008]

I am running the following system:

Apple Macintosh (Intel)
MODEL iMAC
PROC 2.4 GHz Intel Core 2 Duo
RAM 1 GB 667 MHZ DDR2 SDRAM
DRIVE 300 GB

The hanging appears to have been caused when I accidently moved about 40GB of old photo's onto my desktop. Almost immediately I tried to cancel but all that happened is that the system has hung. Processer can be heard working in the background.

Being new to MAC I am pretty stumped.

Have tried the obvious forced restart using the power on/off button but no luck.

Is there a way I can get in and stop this process say at start up?

Thanks

[Satcomer]

Well to stop something starting up is to go to System Preferences(in your Dock)->Accounts, Login Items.