I tried changing the partition type by writing 0c as you say in cfdisk, and then wrote the partition table - and when I exited and entered cfdisk again the patition was no longer hidden. After a reboot though, the partition was hidden again. So, I doubt the problem was the "0".
But, Im out of guesses, so please tell me (as I don't seem to be able to figure it out myself) what is the exact commands I need to use for fdisk: (I have moderately important data on the other partitions and am a bit scared).
1. Change a partition /dev/hdb2 from 1c to c, and write the partition table.
Thanks a bunch homie,