What file system is it formatted with? If it's formatted with a linux fs then Windows will not be able to access it. Have you tried mounting it within Ubuntu?
khurram@HP:~$ fdisk -l khurram@HP:~$
khurram@HP:~$ fdisk -l Disk /dev/sdc: 32.0 GB, 32018268160 bytes 170 heads, 53 sectors/track, 6940 cylinders, total 62535680 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Device Boot Start End Blocks Id System /dev/sdc1 8192 62535679 31263744 c W95 FAT32 (LBA)