That’s a weird problem. Have you tried to assign a driveletter to the space you can’t use by rightclicking the not-usable partition, selecting Change Drive Letter and Paths and assigning a new driveletter?
As far as I know marking a partition as Active has nothing to do with the possibility to access data from it…
I have a Toshiba Portable HDD 120GB partitioned in two drives, one FAT32, other in NTFS, both as logical drives. What is happening is that, when connected to my machine running WS2008 Standard, it only sees one of these partitions. When I go to Disk Management they are both there, but I can make usable just one of them at once, changing between then after checking “Mark partition as active” and restarting the system.
When it is connected to a Windows XP machine both partitions are recognized and usable. Any clue about what’s going on?