Your message is not clear, also you can change job w/o GC

The procedure is:
CIS request -> FBI NC -> CIS HQ Review -> CIS OFFICE

>I was notified on Feb 28 2007 that my NC was finalized and >the result was forwarded to USCIS on Feb 23 2007.

Notified by whom? FBI or CIS OFFICE

>But I was told that the NC is still pending when I >called TSC today.

Could stuck in CIS HQ Reveiw, if they see something fishy, then a second nc request may be sent to FBI.

>I feel very frustrated because I hope to have it >approved so that I can change to another job. My current >boss is so mean. Any thoughts are highly appreciated.

Why wait for GC? If you want to switch job, just go ahead with AC21.

Just my 2c