Please optimize your Lightroom catalog from File>>Optimize Catalog and let us know if that helps.
Also Post a screenshot of your Lightroom Develop Module.
Create a new Catalog in Lightroom from File>>New catalog and import few images to test if it works fine.
If that does not works fine too, then
Backup your Catalog and Reset Lightroom preferences.Refer Recover catalog and images after resetting preferences in Lightroom
Thanks that seems to have worked, took some time finding the Library folder!
Before the reset a new collection did not have any problem the existing ones did.
Once again thanks for the help and prompt response