MMEX goes unresponsive - using 50% CPU

[Janet]

Hello
OS: Windows 10. MMEX v.1.3.3

I had been using a old (b/w) version of MMEX very happily for years. Yesterday, it became unresponsive as soon as I tried to enter figures in a new transaction.
I upgraded to v.1.3.3, but still had the same problem.
I saved to database, uninstalled and reinstalled v.1.3.3. Still the same problem.
I have a techie visiting who renamed the database and, after some fiddling, I can use MMEX, but it is still using a large amount of CPU at times, when MMEX seizes up.

How can I fix this problem? (What further information do you need?)

Thanking you in advance for you help and advice
regards
Janet