I have a few computers at home all running windows 7 pro (apart from my work surface pro 3 and a window rt tablet).  They have been running fine for months all able to talk to each other, share files etc.  Main use for most of them is KODI

The other day on my HTPC, with all my media on it (3 internal 4tb media, one internal 1tb OS, 2 external 3tb media),  windows started up, hung on the load up screen and then wanted to check one of the internal media drives.  I cancelled the check disk and checked it from within windows - all good, then run sea tools on it and also all good.

This is a brand new 4tb that replaced a 2tb that also triggered a check disk (it wasn't all good).

Since then it has been running fine,

However I am unable to access the internal drives through network share, I get the you do not have permission contact your network admin, the externals are fine I can read and write.  The windows rt is unable to even see the HTPC through network or homegroup

I have restarted all devices a number of times
I have removed share and re-shared the drives
I have closed the homegroup and restarted homegroup.

I really don't know what is going on.