I've had problems with my hard drive ever since I got it a year ago. For the most part, it works fine, but whenever I try to do anything with partitions, namely adding or resizing, some of the data in my other partitions inevitably corrupts. I've tried formatting my entire drive, but to no avail. What's going on?
I was going to suggest that the sum of the sizes of the partitions is greater than the physical size of the hard drive.
One obvious thing to remember is to shrink the size of one partition before expanding the size of another.
Don't forget that a 250GB hard drive "only" has ~232GB of space, for example, due to the different way sizes are measures. The manufacturers call 1,000,000 bytes a GigaByte whereas the OS refers to 1,048,576 (1,024 * 1,024) bytes as a GigaByte.
What size is your hard drive, and how many partitions do you have and what sizes are they?