What causes Event 36, volsnap - Shadow copies failed....

Hi,

I keep noticing event viewer produces an

Event 36, volsnap - The shadow copies of volume C: were aborted because the shadow copy storage could not grow due to a user imposed limit.

I am really really curious as to what causes this error. There appears to be little knowledge on this error around the forums yet a lot of people complain about this error. The usual advise is to 'increase your shadow copy storage limit, but in my case the current usage is never no where near my setting of 10GB when the error occurs. I have tried absolutely everything to diagnose this message so far with absolutely no success. Any idea what this message is all about?

The only things I can conclude so far:
This error has occurred over multiple windows 7 installations/hardware configurations so I am fairly certain I cant blame anything hardware/windows 7 corruption related.

The error seems to have started to occur more frequently (but not the sole cause) since setting up MyDefrag to run on a regular daily basis.

I assume the error is related to the attempt that Windows 7 makes to run a system restore point/shadowcopy (one of the same????) automatically (not the ones made when installing/uninstalling software/updates).

Sometimes after Event 36 (but not always) the reported Current Usage under System Protection settings reads 0!

Is this error related to when something interrupts Windows 7 automatic attempt at a system restore point i.e. running Mydefrag/breathing on keyboard?

Where does this mysterious message come from? What causes it? Why such few posts on this? Why do I keep getting scolded by Windows 7 because of my user imposed limit when I am totally innocent?

Error time is usually around the first time I switch on/wake machine in morning.

Please help!

Yep tried that one.