Symbols Folder on my D: drive

[#1]

I have just noticed a folder "Symbols" on my D; drive which has over 4000 files and takes up 860MB
Anyone have any idea what it is - this is a list of the sub folders

[#2]

did you install a "debug" version of your OS at some point?
This directory contains the debug information for the majority of your Windows system dll's.
If you are still running the debug version of your OS, then do not delete the directory.  If you since reinstalled with a standard version, you should be able to safely delete them.
B.

[#3]

Thanks - that's it - i installed debugging tools for windows to try and sort out a problem