computer not entering bios setup

i have inspiron 1100.....well actually, i inserted bootable Mandrake 10.1 Linux...i have installed it before......but this time.As, it prompted the first screen, after bootin from cd....my computer restarted without any reason or pushin of a button...and since then my computer is not bootin from any bootable cd....and it is also not entering bios setup....and i have double checked my cd and F2 key boot are workin absolutely fine....plz, if any one has any idea reply me back..asap...