Builds since 2003-11-21 do not work with Tabbrowser Extensions (the fault is with TBE, not Firebird), so I'd given up on nightlies since. But this major regression-free build had me coming back and searching for a fix to this incompatibility. And guess what? There is a fix, provided kindly by me4get at the Mozillazine forums. The related thread is entitled Updated TBE for Mozilla/5.0 (Gecko/20031121) and you can install the updated TBE by clicking here.
I'm using scragz's optimized builds - fast and works great!
Source: The Burning Edge