I already encountered this error with an AWE32
It happened when I instaled it in my computer and only under dos 7.1
It worked correctly under dos 6.22 and win98 dosbox
It disappeared (mysteriously) when I reinstalled Win98

I think it is somthing to deal with PnP

Try with only CTCM, remove SET BLASTER and DIAGNOSE from your autoexec.bat

I have the same problem now and not found any solution 🙁
Under dos6.22 and win98 dosbox it works just fine but in pure dos7.1 is not.

Offtop: anyone has any AWE64 without ide cdrom interface? (value / gold). It has ide controller in pnp config or not?

I also encountered the problem once, when switching between an AWE64 Gold and a normal AWE64. Unfortunately I don't remember how I fixed it, but I reckon it was something trivial, like deleting or editing the CTPNP.CFG file.
If you have Win9x installed, there is also a CTPNP.CFG file in the Windows directory, which could conflict with the one located in the SB16 DOS drivers directory. To avoid problems, I make sure that all instances of CTPNP.CFG have the same contents:
1) Delete all CTPNP.CFG files on the disk. CTCM will complain that the configuration has changed and suggests starting Win9x to create a new config file.
2) Start Win9x and set the desired resources for the card in the device manager (e.g.: I/O 220,330,620; IRQ 5; DMA 1,5). This will generate a new CTPNP.CFG in the Windows directory.
3) Copy the CTPNP.CFG from the Windows directory to your SB16 drivers directory (the one where CTCM is located).

c.imp wrote:

Offtop: anyone has any AWE64 without ide cdrom interface? (value / gold). It has ide controller in pnp config or not?

PnP SoundBlasters without IDE interface don't have the IDE section in the PnP config.