If you can run DeSmuME you should already be running it instead of No$gba. It is superior in every way.
If however you can't get DeSmuME to run fast enough, try setting the Reset/Startup Entrypoint (under No$gba Settings (F11)) to GBA BIOS, as stated above by machomuu.
If that doesn't work, get the 2 BIOS files and the Firmware.bin file, put all three in the same folder as No$gba and No$Zoomer. Then try again.
I won't link to them here but you should be able to find them with a quick google search ("biosarm7.rom, biosarm9.rom and firmware.bin")
If that still doesn't work go and use DeSmuME already.