@jesus prieto. I certainly will do. I'm looking forward to being able to use Studio again as normal. So fingers crossed.

@jesus prieto and

Update... SDL's helpdesk accessed my computer remotely but couldn't solve the problem. They said that it was probably corrupt user settings on my computer.

Apparently, there were no Windows corruptions and they couldn't locate the problem in Multiterm or Studio. 

So, the case is closed.

Now, thinking again, I don't understand why the rest of my computer and all other programs work fine. 

If I install my SDL licence on another computer, will I take the problem with me? Very worrying! And I now have TM problems in Studio, too. It's like the problem is spreading.

Sorry to hear that.

I'd say it's time to schedule a fresh PC setup from scratch: formatting the C drive and installing Windows + Trados Studio + MultiTerm.

@jesus prieto.

Oh dear - extremely daunting.