this should be issue with the consolidation , if you click on the vm and check the summary , you might see the Consolidation warning ,
either click on "cosolidate" from the gui , or use cli to remove the snapshot file
Thanks and Regards,
Nithyanathan R
Please follow my page and Blog for more updates.
Blog : https://communities.vmware.com/blogs/Nithyanathan
Twitter @Nithy55
Facebook Vmware page : https://www.facebook.com/Virtualizationworld