[Parameter 1] 0xD, 0xE, 0xF, 0x23, 0x24, 0x25 [Parameter 2] Reserved [Parameter 3] Reserved [Parameter 4] Reserved [Cause of Error] 
The pool header of a freed block has been modified after it was freed. This is not typically the fault of the prior owner of the freed block; instead it is usually (but not always) due to the block preceding the freed block being overrun.