When i put my usb, my computer crash

iMac 24 inch

This is the report:

Mon Apr 6 18:45:07 2009
panic(cpu 0 caller 0x003EB97C): "IOUSBDevice::_RESERVEDIOUSBDevice8 called\n"@/SourceCache/xnu/xnu-1228.9.59/libkern/c++/OSMetaClass.cpp:816
Backtrace (CPU 0), Frame : Return Address (4 potential args on stack)
0x69d839e8 : 0x12b4f3 (0x45b13c 0x69d83a1c 0x1335e4 0x0)
0x69d83a38 : 0x3eb97c (0x49c500 0x5e51f4 0x5e51f4 0x8)
0x69d83a58 : 0x5c1812 (0x5f6c18 0x8 0x69d83a88 0x3ece8f)
0x69d83a78 : 0x5b270b66 (0x6bccc00 0x69d83a9c 0x69d83aa8 0x3f0459)
0x69d83aa8 : 0x5b2719ce (0x6aed600 0x5b276ad4 0x6b933e0 0x0)
0x69d83af8 : 0x412976 (0x6aed600 0x6bccb00 0x1 0x3ecd96)
0x69d83b58 : 0x414219 (0x6bccb00 0x6aed600 0x6beaa60 0x6bef080)
0x69d83bd8 : 0x413a7d (0x6bccb00 0x6bc4100 0x0 0x1)
0x69d83c28 : 0x414786 (0x6bccb00 0x2 0x6bccb00 0x0)
0x69d83c68 : 0x40e528 (0x6bccb00 0x2 0x1 0x5aeaa2)
0x69d83ca8 : 0x5be73d (0x6bccb00 0x2 0x5e6a7c 0x6aec3e0)
0x69d83d28 : 0xa0bf7d (0x6bccc00 0x6b82400 0x1 0x1)
0x69d83d58 : 0xa0b2db (0x6b82400 0x1 0x1 0x0)
0x69d83df8 : 0xa0a565 (0x6b82400 0x5f6c18 0x69d83e48 0x40fdd6)
0x69d83e48 : 0x412976 (0x6b82400 0x6bccc00 0x1 0x3ecd96)
0x69d83ea8 : 0x414219 (0x6bccc00 0x6b82400 0x6bea300 0x6bea660)
Backtrace continues...
Kernel loadable modules in backtrace (with dependencies):
com.apple.iokit.IOUSBMassStorageClass(2.0.4)@0x5b2 6f000->0x5b278fff
dependency: com.apple.iokit.IOSCSIArchitectureModelFamily(2.0. 5)@0x848000
dependency: com.apple.iokit.IOUSBFamily(3.1.5)@0x5a2000
dependency: com.apple.iokit.IOStorageFamily(1.5.5)@0x861000
dependency: com.apple.iokit.IOUSBFamily(3.1.5)@0x5a2000

BSD process name corresponding to current thread: kernel_task

Mac OS version:

Kernel version:
Darwin Kernel Version 9.6.0: Mon Nov 24 17:37:00 PST 2008; root:xnu-1228.9.59~1/RELEASE_I386
System model name: iMac8,1 (Mac-F227BEC8)