The timeout happens to me occasionally outside of vmware.
Re-starting without a backup will not fix things as extensions are downloaded to permanent storage unless you are booting from an iso in the vm every time.
Assuming your extensions folder is at /mnt/sda1/tce/optional and your download timed out whilst downloading an extension named extension_name, you would delete it like this: $ rm /mnt/sda1/tce/optional/extension_name.tcz*