You have proven something is wrong with the machine. The extender errors usually indicated bad ram.
Look up MEMTEST86 and try that test.
Best of luck,
My mother-in-law has a fairly old PC that ran on MS-Millennium. Yes, I know it's crap so please don't remind me. The PC died a death a couple of days ago and I was asked if I could have a look at it. I brought it home, set it up and booted. Power supply appears to be okay, HDD ditto, both lights were on. Having said that there were no 'beeps', and the monitor, mouse and keyboard were as dead as a dodo. I did the obvious, I changed the power supply, and this time there was 'beeps', and all the usual lights, keyboard and mouse came to life. It wouldn't boot. I suspected that the OS had been corrupted in some way and decided to clean the drive and start clean. I fdisk'd and reformated the HDD, and using EZ reinstall I attempted to replace the OS ... it was having none of it. I kept / keep receiving the message; "Standard Mode; fault in MS-Dos extender" followed by these letters and numbers; EC=0000, CS=0053, IP=232F, AX=0000, BX=0FEE, CX=0000, DX=FFF0, SI=35EC, DI=FFE8, BP=0000, DS=004B, ES=0000, SS=004B, SP=00E2.
Regardless of what I try, this message reappears halting the reinstalation. I have even tried wiping the HDD and installing MS-Dos 6.22 ... Win 3.1 ... Win 95 ... Win 98 ... and nothing seems to work.
If anybody has any (sensible) ideas, I would be very grateful.