Apologies for bumping my own thread - this is turning me crazy and can't make any sense out of it, so again trying to find some knowledge with new information. Please help me for my own sanity! 😁

Here's what I done:
- I've removed everything but the IO and VGA cards
- I've reset BIOS to default
- I've started fresh from empty config.sys (only loading the IO driver) and a fresh autoexec.bat (only loading ctmouse)
- I've checked the jumpers on the IO card for Serial Config (no reason they changed but still)
- I've tried latest alpha from cutemouse, as well as latest stable
- I went crazy because it used to work fine and I can't figure out what changed, at this stage the only rational explanation is that it just randomly stopped working...which doesn't satisfy me

Here are a few screens:

BIOS screen showing COM ports as 3F8h and 2F8h

Driver NOT loaded - ctmouse detects mouse fine, and comtest shows proper COM ports and addresses. Why is it detecting a modem on COM2 is a mystery though, nothing is connected to COM2.

Driver NOT loaded - SysInfo shows proper COM1/IRQ4 used by ctmouse

Driver loaded - ctmouse finds no device and comtest shows nothing

Driver loaded - SysInfo shows COM ports normally and available...

Driver config screen showing COM ports enabled with the proper address...

I really hope someone comes up with an idea because I really want to keep using the driver.

I'll happily wager sending a fair amount of Swiss chocolate over to the one that finds the solution to that mystery, as a fun expression of my deep gratitude 😁 this still stands if it's just me being stupid and/or uneducated and hopefully I'll learn something new!

I believe when you mess around with that UM8672.SYS menu it creates a hidden configuration file directly under C:\. You may need to use with ATTRIB to see it, and make it so you can get to it. It may be best to delete that file and start over.

You're the man!

So yes indeed it creates a 13 bytes file called 863data in the root. What's funny is that that file is only created when going into the driver setup screen...and once the file exists, mouse fails.
If I delete it and never go in the config screen, it properly detects and sets my drive to fastest speed (which is basically the only reason I'm using it), the file doesn't get created and mouse works fine.

Sounds really weird to me but that's more than good enough for me - as long as my ports work and I still get the nice performance boost!

Fancy some chocolate? I'm dead serious 😁 I've wasted hours the past few days on that crap!

EDIT: checked my PM's and knew your name was familiar, you're the guy that shared his custom made driver to optimize performance 😉 looks like you know your UMC 8672 pretty well 🤣!