I've been asked by a friend to help free disk space on her C: drive. When I look I find her C: is allocated 39gb and is full. She has a D: partition that is well over 400gb and is 7% used.

My first thought is to shrink the D:, no problem, then allocate that space to the C:.

I did some research and see warnings that expanding the C: could corrupt the O/S. However I can't find anyone who has actually experienced corruption. Is it a valid concern?

The other note I found said that only contiguous space can be added when expanding. On her drive she has as follows:

39gb unallocated
39gb SYSC: NTFS, Healthy
39gb unallocated
365gb SYSD:
122gb unallocated

Can I safely expand the C: to use anything other than just the one 39gb space immediately after it?