Preferred Networks not saving

[jaywongy]

I have recently downgraded form Lion 10.7 with various problems which have been solved. However, I have now realised that when I restart my iMac it does not remember my network. When I try and save my router as a preferred network it crashes giving me the error code:

Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x0000000000000060
Crashed Thread: 0 Dispatch queue: com.apple.main-thread

Could somebody please help me, as it is quite annoying having to select my router every time I restart...