I'm pretty sure that this is a BIOS limitation of the 8600 which means that it won't recognize a hard drive greater than 137GB. If you try to use partitions above the 137GB limit then you are eventually going to run into trouble (data corruption). The only solution is to create any partitions in the first 137GB of the disk and just ignore the rest. Alternatively, you could check the Dell web site to see if there is an updated BIOS to avoid this problem.
Google "Inspiron 8600 137" for more information.