This is because HWiNFO requires quite much system memory available and you need to free as much as possible.
Thus please review your DOS Bootable media settings, remove any unnecessary drivers or residenent programs loaded before HWiNFO start.
The best option is to use pure MS-DOS 5.00 and later with XMS Memory Manager (HIMEM.SYS) and load all possible devices and part of DOS HIGH (DOS=HIGH, LOADHIGH, etc).
Alternatively, an EMM manager like (EMM386.EXE) can be used too together with the UMB option.
Here's a sample of CONFIG.SYS content:
DEVICE=HIMEM.SYS
DOS=HIGH
AUTOEXEC.BAT doesn't require anything special and best option is an empty file.
Nothing more is required for HWiNFO to run (in case you don't need any special drivers to be loaded).