issuing SIDT _crashes_ the system?!

Hello, I tried getting the interrupt descriptor table register (IDTR) using sidt but... the system crashed? it first told me about a null pointer dereference (sorry, haven't got the oops any more) and then all processes died away. on the console i repeatedly got the message "no vm86 information:

interrupt magic

Hello, I'm currently using 2.4.0-test5 and no APIC. I'm trying to learn a bit about protected mode programming on i386 architectures. Looking at the interrupts, the interrupt descriptor table, interrupt gates and all those things I wanted to experiment a bit to see if I understood correctly. S