I got a Vers.4 MCB900 board and my LPC932 chip was revision C.
When I started FlashMagic it always showed that Unable to read the security bits.
Any command in ISP menu I selected caused the error message of unable to connect to the device.
Doesn't MCB900 Vers.4 support the LPC932 Rev.C ?
Is your device brand new or has it ever been programmed?
Rev C devices do not support the hardware entry method, and can only enter ISP mode using break detect. This is something you have to enable in your code, so if that wasn't done you cannot get back into ISP mode again.