Thanks for replying Clive, and apologies for the delay in responding. It appears the issue may be caused by corruption of some of the database tables.
I tried myisamchk (the check and repair tool) with various parameters and it made no difference. Running -r for recover resulted in it finding some errors and supposedly recovering them, only for the same thing to happen when it was run again.
I am working on restoring the database from a copy.
I think that it may have got corrupted when XAMPP crashed out. I was getting the error about not being able to create xampp-control.ini, a common issue it would seem. Each time I found the only way out was to end the process through Task Manager. I have rectified this and XAMPP now closes without issue.