Good point! Now that you mentioned it, I just realize that, in fact, I had downloaded w6163v27.exe a few weeks before getting my hands on the board.
However, I totally forgot about it and I just went with the MSI website download once I started playing with it.
Will try it and get back to you.

So, yeah, just flashed it and the FSB frequency set in the BIOS now matches the actual FSB frequency. Other than that... things look the same: did a few tests, it's stable as before.
Thanks for the heads up!

this is a BX board right? make sure your AGP card is stable at 88MHz...

It is stable (and I have four other 440BX boards which are all stable at 133 MHz FSB with 89MHz AGP, when using nVidia cards).
I'm using GeForce 3 Ti 200 / GeForce 4 Ti 4200 on these boards (a "bit" overpowered, I know). But I also tested cards like GeForce 2 GTS / GeForce 2 Ti and didn't see any instability.

ahh yeah the Nvidia cards handle 88MHz AGP like a champ, ATI no so much