DOS Conventional Memory

I have a pentium 150 Mhz computer running DOS 6.0 and Windows 3.1. I have been running Generic CADD on this computer for a long time, but all of a sudden, some graphics are showing out of memory.
The program settings have not changed.
What seems different is that on a “mem” display, I show only 155KB of upper memory available. Should that not be more like 384KB?
When I display the details of “mem” utilization, I don’t see anything that does not belong.
At this time, my only option is to remove drivers, which changes the working environment for the client.
The HIMEM and EMM386 programs are the DOS ones, not the Windows ones.
EMM386 is also NOEMS setting.

any suggestion?

thanks

gilles mailhiot