Your harddisk is using the Dynamic Disk Format, which is not compatible with Linux and some Windows Version (Home Editions). Windows allows you to convert every disk to a Dynamic Disk but not back to a Basic Disk. Dynamic Disk format is used to provide features like Software RAID. You're setup doesnt seem to use such a feature, therefor you can safely use the Basic Disk format.

You can backup all your data, delete all partitions and create a new partition table (make sure you don't convert it to a Dynamic Disk again).

There are ways to convert this disk back to a Basic Disk without copy all data around. This Blog entry describes a method using Test Disk. But be careful, and as always, make a backup first!