I have a bizzare situation where a known working combination of a CF IDE adapter and CF card causes corrupted screen in BIOS and hangs the computer later. The only configuration where card works and the screen is fine is having the adapter in primary controller with a jumper set to slave on the CF adapter (still detected as master). All other configurations either hang the system immediately (before BIOS) or corrupt screen and hang it later. Tried fours different cards - same effect.

The system works fine otherwise with two IDE HDDs (primary and secondary) and CD (slave on primary) running DOS. Pulling out various ISA cards didn't have any effect.

The CF cards and adapter work fine on a P Pro system.

The system is 486DX2 with Jetway 435-B motherboard.

Any ideas what might be happening here?