This provisioned space has come from no where.
The provisioned size does not change automatically, but only manually. From the provisioned size of the first virtual disk (the one in question) it looks like this was created with 45GB and then someone decided to only use 10GB and create a second disk with 35GB!?
Unless this host is part of an HA cluster and memory is not overprovisioned, you could set a memory reservation for the VM. This will result in a reduced size for the .vswp file which is created when the VM is powered on, effectively freeing up disk space to be able to power on the VM.
André