Seems the new skype has made it hard to clear it's cache. Here are the steps to clear it.

in the windows search box (windows 10) type in:

run

and hit enter

In the popup type in the following:

%APPDATA%\Microsoft\Skype for Desktop\Cache

and hit enter

It should open a Window in the appdata/Microsoft/Skype for Desktop/Cache. Delete all the files in this area.  You might have to sign out of skype while doing this to delete them all.

Once done sign into skype again.