ESP32 I2C misbehaving

[rholmesa]

Hi,
My first post here - I have just started playing ...

I am having trouble with my ESP32 when attempting to use I2C from the 'standard' pins 21 and 22.

I have an I2C Adafruit 128 * 64 Oled board which HAS worked well with this configuration, and I can 'detect' the I2C address using standard software for the purpose. However, now I have come to reprogram the ESP32 (again with a standard test program) I am getting the following error:

Guru Meditation Error: Core 1 panic'ed (IntegerDivideByZero). Exception was unhandled.
Core 1 register dump:
PC : 0x400d24d0 PS : 0x00060730 A0 : 0x800d20a0 A1 : 0x3ffb1f20
A2 : 0x3ffbdc54 A3 : 0x00000000 A4 : 0x00000001 A5 : 0x00000015
A6 : 0x00000000 A7 : 0x3ffbdc54 A8 : 0x800d24d0 A9 : 0x3ffb1ef0
A10 : 0x04c4b400 A11 : 0x00000016 A12 : 0x00000000 A13 : 0x00000064
A14 : 0x00000000 A15 : 0x60013000 SAR : 0x0000000a EXCCAUSE: 0x00000006
EXCVADDR: 0x00000000 LBEG : 0x4000c46c LEND : 0x4000c477 LCOUNT : 0x00000000

ELF file SHA256: 0000000000000000

Backtrace: 0x400d24d0:0x3ffb1f20 0x400d209d:0x3ffb1f40 0x400d1706:0x3ffb1f60 0x400d0ce4:0x3ffb1f90 0x400d38e2:0x3ffb1fb0 0x4008686d:0x3ffb1fd0

Having done some investigation, it appears that an item called clk_speed is being passed as zero in one of the libraries, hence the divide by zero. I have tried different Oled boards AND ESP32 boards, but it always ends up the same.

What I don't understand is why this has started happening when it was previously ok.
Can anyone throw any light on this?