Photoshop crashes unexpectedly

Question

Hi all,
If you can decipher what any of this means below, I'd much appreciate it. I'm mainly using this machine to run Photoshop, and it crashes unexpectedly while I'm painting. Please...any ideas would be great. Thanks so much.
Problem Details:
Process: Adobe Photoshop CS3 [16200]
Path: /Applications/Adobe Photoshop CS3/Adobe Photoshop CS3.app/Contents/MacOS/Adobe Photoshop CS3
Identifier: com.adobe.Photoshop
Version: 10.0.1 (10.0.1x20071012 [20071012.r.1644 2007/10/12:09:30:00 cutoff; r branch]) (10.0.1)
Code Type: X86 (Native)
Parent Process: launchd [66]
Date/Time: 2008-02-22 22:09:35.053 -0800
OS Version: Mac OS X 10.5.2 (9C31)
Report Version: 6
Exception Type: EXC_BREAKPOINT (SIGTRAP)
Exception Codes: 0x0000000000000002, 0x0000000000000000
Crashed Thread: 7
Application Specific Information:
* Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '* -[NSCFArray extent]: unrecognized selector sent to instance 0x20ff8bf0'
((((there's more of this, but this seems to be the important bit. Let me know if you want more from that readout))))
System Configuration:
Model: iMac7,1, BootROM IM71.007A.B01, 2 processors, Intel Core 2 Duo, 2.8 GHz, 4 GB
Graphics: kHW_ATIr600M76Item, ATI,RadeonHD2600, spdisplayspciedevice, 256 MB
Memory Module: BANK 0/DIMM0, 2 GB, DDR2 SDRAM, 667 MHz
Memory Module: BANK 1/DIMM1, 2 GB, DDR2 SDRAM, 667 MHz
AirPort: spairportwireless_card_type_airportextreme (0x14E4, 0x88), Broadcom BCM43xx 1.0 (4.170.46.3)
Bluetooth: Version 2.1.0f14, 2 service, 1 devices, 1 incoming serial ports
Network Service: Ethernet, Ethernet, en0
Serial ATA Device: Hitachi HDS721010KLA330, 931.51 GB
Parallel ATA Device: PIONEER DVD-RW DVR-K06A
USB Device: Keyboard Hub, Apple, Inc., high_speed, 500 mA
USB Device: Apple Keyboard, Apple, Inc, low_speed, 100 mA
USB Device: Built-in iSight, Apple Inc., high_speed, 500 mA
USB Device: Bluetooth USB Host Controller, Apple, Inc., full_speed, 500 mA
USB Device: PTZ-930, Tablet, full_speed, 500 mA
USB Device: IR Receiver, Apple Computer, Inc., low_speed, 500 mA
USB Device: Apple Optical USB Mouse, Mitsumi Electric, low_speed, 500 mA
FireWire Device: My Book, WD, 400mbit_speed

Answer 1

Hi George,
I have just Photoshop CS3. I did not migrate from another computer. I can't imagine I'd run out of ram, since I paint in Photoshop at work all day on a PC computer that only has 2GB of RAM, and a scratch disk size way smaller than my iMac. But then again, this is my first Mac computer, I've never worked on one before.
I haven't changed my default Mem Usage (which is at 70%, or 2150 MB) and I haven't changed my default Scratch Disk either (which is my current home drive, with 753 GB free space).