Reporting of free disk space improper for my Mac SSD

Frequently I find that the reported free disk space shown on the desktop for my Mac SSD is wrong since I upgraded to 10.10.3

This is just a reporting issue since the disk utilities I have checked show the correct amount of free space.

To fix it I go to preferences and open Time Machine and turn it off, and then back on.....this has corrected the issue.

Just reporting this in case others are having the same issue.