I've recently played a bit with UMBs on 9x, and I've triggered something, that looks like a bug. After adding LocalLoadHigh=1 to my system.ini 386Enh section, .bat files end with the MICROSOFT WINDOWS POP-UP PROGRAM SUPPORT message. And this will happen on batch files, as simple as a one-liner calling dir. I found reports of such behaviour on usenet group posts from the 90s, but no one provided a solution except for removing the line.

To reproduce the problem:
1) Enable UMBs in CONFIG.SYS, either by EMM386 RAM or UMBPCI.SYS, since both trigger the behaviour and by adding DOS=HIGH,UMB.
2) Add LocalLoadHigh=1 to system.ini 386Enh section.
3) Create a .bat file with just the command dir inside and run it. It should finish and end with a MICROSOFT WINDOWS POP-UP PROGRAM SUPPORT message requiring you to press Ctrl+C to close the window.

The question is: can you reproduce it? If not, what is your configuration? I've triggered this both on a 430FX and 440BX motherboard with 95 OSR2 and 98 SE. Maybe someone knows how to not trigger it with `LocalLoadHigh=1` (running command /low /c batchfile.bat is not a solution, since it essentially is the opposite of what this option does)?