My LRc catalogue is behaving strangely

My main catalogue has been slowing down and generally being a bit glitchy for a while, then recently I had a corrupt error message. It was successfully repaired but has been growing progressively more and more unuseable ever since because it's behaving very strangely;

1. Generally being unreasonably slow
2. I've had images which have been edited randomly reverting to raw when they're clicked (when I go on history the last edit is still there so I click on it to restore, but this happens so frequently it's not a reasonable workaround).

3. It often stalls when navigating back and forth through a collection. So for example I might be viewing a particular image, then when I click another image or advance using the keys, the desired image is selected but the previous image is still showing. I have to go back and forth a number of times before it settles down. 

4. Edits from PS are rendomly corrupting.

5. I can't import anything into the catalogue. It just sits there when you click import and doesn't show any images available. I am able to import from another catalogue, just not from devices, hard-drives or Aftershoot.

5. Weirdest of all; I recently hit 'Denoise and the below happened. A bunch of green surrounding the images and in the presets pane, plus complete gibberish in the top left progress bar. Surprisingly the denoise actually completed and then everything went back to normal but I didn't dare touch it anymore after that and I'm worried that the catalogue is teetering on imminent and total faliure. I back up daily and use the optimise feature. I've even tested the integrity and it claims it's fine so I had thought it was LRc that was failing but when I set up a temporary catalogue to see what happened I found that one behaved perfectly so I'm now assuming it's the cataglogue which is the problem. I have around 36,000 images in it which from what I gather shouldn't be a problem for LRc. Telephone support has been unhelpful, I wondered if anyone has any advice as to my next steps?