You can either move your projects, or tell an IDE to change it's its mind.
For the latter add the following line to IDE_HOME/bin/ idea.properties file (see this answer for details):
Use true if your projects are located on case-sensitive FS, false otherwise. Then choose File | Invalidate Caches and restart the IDE.
Nope. Setting the global property is a temporary solution; vote/watch this issue to be notified when a permanent fix will be in place.