Can't add drive letter to partition, have 7 primary partitions

[svrich]

Ok i know this sounds stupid (hey, it's windows) but how do I end up with 7 primary partitions? I thought you could only have 4. Anyway, one of my partitions no longer has a drive letter so I can't access anything on it. I'm unable to right click it in disk Management to add one, the option is grayed out (see pic).

1st partition = 100MB win7 boot
2nd partition = the windows OS on it's own 50G partition
3rd partition = 50G FreeBSD Unix (this is a multi-boot system)
4th partition = 500G data partition, the one that lost it's drive letter D:.
5th, 6th, and 7th partitions are Linux partitions and the last one looks like an extended partition by the green outline.

I've used this system successfully since last year when win7 came out. It's worked pretty good but all of a sudden it lost the drive letter for the 500G data partition. I have no idea what happened or how to get it back. Any ideas?

 

[severedsolo]

Shot in the dark:

As you said, you can only have 4 Primary Partitions. I suspect that Windows knows this and is therefore saying "Well that can't be right" and assuming its made a mistake and won't let you assign drive letters.

If you get it down to 4 partitions again, it will probably let you assign letters.